While the top eight women in the world fight it out for season supremacy at the WTA Tour Championships in Istanbul, some of the best rising talent, as well as some of the fallen, will officially end the season at the lower tier Tournament of Champions.

While the Tour Championships brings together the top eight women in the world plus two alternates, the official season-ender brings together the six top-ranked women who have won lower-level titles during the season, as well as two alternates as decided by the tournament’s director.

Players who are either currently playing in Istanbul, or will represent their country in the Fed Cup final on the same weekend, are ineligible to qualify.

This means the likes of Angelique Kerber (who won Linz) and Roberta Vinci (Katowice and Palermo) will not feature in Sofia, despite meeting the criteria for qualification.

Italy and Russia will contest the Fed Cup final next weekend, while Kerber snapped up the last direct plane ticket to Istanbul courtesy of her title victory in Linz last week.

This year’s field promises to be a strong one, with two former Grand Slam champions and two former world number ones are featured in the field.

Caroline Wozniacki
Current world ranking: 10
Titles this year: Luxembourg

2013 Grand Slam results
Australian Open: Fourth round
French Open: Second round
Wimbledon: Second round
US Open: Third round

Tournament of Champions history
Second direct qualification
Best result: Finalist (2012)
Last year’s result: Finalist

It’s been a year of disappointment for former world No. 1 Caroline Wozniacki, who only last week won her first title in 12 months and failed to make an impression at any of the major tournaments in 2013.

The Dane, who last topped the world rankings in January last year, failed to get past the fourth round at any of the Grand Slams this year, and has now gone seven consecutive Slams without doing so.

Her latest failure at a Grand Slam was at the US Open, when she lost in the third round to little known Italian Camila Giorgi.

Wozniacki, a finalist here last year and at the 2010 WTA Tour Championships, can only participate if she is not required to fill in at the higher-level event, where she is one of two alternates along with Sloane Stephens.

Having captured a confidence-boosting title at Luxembourg last week, she will enter the season-ender with a lot of confidence as she attempts to go deep into major tournaments again next year.

Simona Halep
Current world ranking: 14
Titles this year: Nuremburg, ‘s-Hertogenbosch, Budapest, New Haven, Moscow

2013 Grand Slam results
Australian Open: First round
French Open: First round
Wimbledon: Second round
US Open: Fourth round

Tournament of Champions history
Tournament debut
Best result: N/A
Last year’s result: N/A

Now aged 22, 2008 junior French Open champion Simona Halep is undoubtedly the most improved player on the Tour.

The Romanian has made the biggest breakthrough of any player this year, capturing the first five titles of her career and going deep in Rome, claiming some big name scalps along the way.

She reached the fourth round of a Grand Slam for the first time at the US Open, losing to comeback Italian Flavia Pennetta. Elsewhere, she had a pair of first round losses at the Australian and French Opens, and a second round loss at Wimbledon.

The first round loss at the French Open was an anti-climax to her breakthrough tournament. In Rome, she defeated former French Open champion Svetlana Kuznetsova, world number four Agnieszka Radwanska, and former world number one Jelena Jankovic en route to reaching the semi-finals, where she found Serena Williams way too good for her.

That preceded her first career title in Nuremburg, followed by one in ‘s-Hertogenbosch barely a week later, and then in Budapest after Wimbledon.

She then won her first Premier title on the eve of the US Open, upsetting defending champion Petra Kvitova to win in New Haven. And just recently, she upended Samantha Stosur to win in Moscow.

Like Wozniacki, Halep will enter this tournament on the back of a title, and should be considered a serious contender.

Ana Ivanovic
Current world ranking: 16
Titles this year: None (wild-card entry)

2013 Grand Slam results
Australian Open: Fourth round
French Open: Fourth round
Wimbledon: Second round
US Open: Fourth round

Tournament of Champions history
3rd qualification (second as a wild-card entry)
Best result: Won (2010, 2011)
Last year’s result: Did not qualify

After launching herself back into the world’s top 20 early last year, it’s fair to say that Ana Ivanovic has taken a bit of a backwards step this year.

She failed to get past the fourth round at any of the Grand Slams, failed to reach a Premier final for the fourth year in a row, and fell victim to not only some of the world’s top players, but also some unheralded opposition.

The Serb was able to achieve her most important result of the season by reaching the semi-finals in Madrid, losing there to Maria Sharapova. She also recorded an impressive 6-3, 6-1 victory over world No. 6 Angelique Kerber in the quarter-finals.

This would not have happened had Polish nemesis Agnieszka Radwanska not lost in the second round to Laura Robson, whom Ivanovic would defeat in a painful error-fest in the third round, only escaping in a final set tiebreak.

She also reached the semi-finals in Carlsbad, falling to Victoria Azarenka, and was only recently denied her first title in almost two years when she fell to Kerber in Linz.

Having won this tournament twice previously, the former French Open champion will hope to end a disappointing year on a high, but assuming that she does well, she will achieve her first 40-win season since 2007 – an impressive stat given her inability to win a title this year.

Maria Kirilenko
Current world ranking: 18
Titles this year: Pattaya

2013 Grand Slam results
Australian Open: Fourth round
French Open: Quarter-finals
Wimbledon: First round
US Open: Third round

Tournament of Champions history
Second qualification (first as direct qualification)
Best result: Round robin (2012)
Last year’s result: Round robin

One player who impressed in the first half of the season, but disappointed in the second half of it, is 26-year-old Russian Maria Kirilenko.

After reaching the fourth round of the Australian Open, where she was heavily beaten by Serena Williams for the first (of three) time this year, she won her first singles title in over four years by triumphing in Pattaya over Sabine Lisicki.

She then reached the semi-finals at Indian Wells, defeating Agnieszka Radwanska and Petra Kvitova along the way before falling to Maria Sharapova.

A modest clay court campaign followed, reaching the third rounds in Madrid and Rome (falling to Williams and Sara Errani respectively) before following those up with a quarter-final run at the French Open.

Her draw in Paris had opened up following Li Na’s shock second round exit, and she used it to her advantage to reach the final eight for the first time, losing to former doubles partner and good friend Victoria Azarenka.

That saw her enter the top ten for the first time, but her glory would be short-lived as she suffered a first round exit at Wimbledon at the hands of local favourite Laura Robson.

That began her struggles in the second half of the season. She fell heavily to Simona Halep at the US Open, winning only one game in a 50-minute horror show.

She was able to rebound in Beijing though, pushing eventual champion Serena Williams in a tight two-set struggle, both sets being 7-5.

After dropping in the rankings to her current 18, Kirilenko will be desperate to end the season on a high and set herself up for what could be the most important year of her career.

Samantha Stosur
Current world ranking: 19
Titles this year: Carlsbad, Osaka

2013 Grand Slam results
Australian Open: Second round
French Open: Third round
Wimbledon: Third round
US Open: First round

Tournament of Champions history
second direct qualification
Best result: Round robin (2009)
Last year’s result: Did not qualify (alternate for WTA Tour Championships)

It may have been a wretched year overall for Samantha Stosur, but whenever she had the chance to realise her potential, she did.

Two titles this year, one victory each over Agnieszka Radwanska, Petra Kvitova and Victoria Azarenka, as well as a run to the final in Moscow were enough to make up for her Grand Slam flops, which saw her fall before the third round at all four Slams.

Her traditional struggles at home were quickly forgotten as she reached a hat-trick of quarter-finals in Doha (lost to Maria Sharapova), Dubai (lost to Roberta Vinci) and Indian Wells (withdrew before match against Angelique Kerber) before disaster struck.

A calf injury she suffered in her victory over Mona Barthel at Indian Wells forced her withdrawal from Miami, destroying all the confidence she had built in the previous month.

A poor clay court campaign followed, but she was able to reach the quarter-finals in Rome after defeating Petra Kvitova for the first time after four previous losses, including in a Fed Cup tie where Stosur held a match point in the second set before capitulating.

At Wimbledon, Stosur reached the third round for only the second time. After emphatic victories over Anna Karolina Schmiedlova and Olga Puchkova, she fell to eventual finalist Sabine Lisicki in three sets.

After flopping early in Stanford, she then won her first title in 100 weeks in Carlsbad, defeating Victoria Azarenka for the first time in eight attempts in the championship match. This came after she defeated Agnieszka Radwanska in the quarter-finals, extending her impressive record against the Pole to 3-1.

But the US Open would be where it would all go wrong. She fell in the first round to world number 296 Victoria Duval, a survivor of the Haitian earthquake in 2010.

A pair of losses to Lucie Safarova in Tokyo and Beijing followed, before she was able to win the title which qualified her for this event in Osaka, defeating two rising stars, Madison Keys and Eugenie Bouchard, on her way to the title.

And just last week, in Moscow, she reached the final for the second consecutive year, falling this time to Simona Halep, after prior victories over Kaia Kanepi, Ana Ivanovic and Svetlana Kuznetsova.

This will be Stosur’s second appearance at the event, and the fifth consecutive year that her season has ended at either of the two year-end championships.

Having built so much confidence in the past month, Stosur will want to do well in Sofia as the dreaded Australian summer looms.

Elena Vesnina
Current world ranking: 25
Titles this year: Hobart, Eastbourne

2013 Grand Slam results
Australian Open: Fourth round
French Open: First round
Wimbledon: Second round
US Open: Second round

Tournament of Champions history
Tournament debut
Best result: N/A
Last year’s result: N/A

Another player enjoying her breakthrough this year is Russia’s Elena Vesnina, who after six previous losses in tournament finals was finally able to capture the first two titles of her career this year.

The first came in Hobart, where she usurped Germany’s Mona Barthel to finally capture her first career title, and the second an important one in Eastbourne, where she won her first Premier title at the expense of Jamie Hampton.

Her Grand Slam results have been a bit dire; apart from reaching the fourth round of the Australian Open, she fell early at the rest, losing in the first round in Paris and falling in the second rounds of Wimbledon and the US Open.

She has, however, achieved some big victories this year, including saving a match point to defeat Roberta Vinci in Australia and also upending Ana Ivanovic and Li Na on her way to the Eastbourne title.

After her breakthrough this year, a third title should prove possible for the veteran Russian, stuck behind the shadow of many of her more successful compatriots in recent years. Now is the time for her to stand up.

Anastasia Pavlyuchenkova
Current world ranking: 26
Titles this year: Monterrey, Portugal

2013 Grand Slam results
Australian Open: First round
French Open: Second round
Wimbledon: First round
US Open: Third round

Tournament of Champions history
Second qualification
Best result: Quarter-finals (2010)
Last year’s result: Did not qualify

The third Russian in this year’s field is former top 15 player Anastasia Pavlyuchenkova, who has enjoyed somewhat of a resurgence this year after a title-less 2012.

The 22-year-old started this year by reaching her first Premier final in Brisbane, falling victim to Serena Williams, who would claim the first of her 10 titles so far this year. She reached the final by knocking out Petra Kvitova and Angelique Kerber on the way.

This would not translate into success at the Australian Open, where she lost in the first round to Lesia Tsurenko, who she’d beaten in the semi-finals in Brisbane.

A string of disappointing showings across the Middle East and the early American swing followed, before the Russian ended her two-year title spell by winning in Monterrey, the scene of her most recent title back in 2011.

She then won her second title in as many weeks, and her first clay court title, by triumphing in Portugal, before the remainder of her season saw her endure some poor results.

She fell in the first round in Madrid to Victoria Azarenka, the second round of the French Open to Petra Cetkovska, the first round at Wimbledon to Tsvetana Pironkova, the second round of the Rogers Cup to Li Na and in the third round of the US Open to world number four Agnieszka Radwanska, among others.

Pavlyuchenkova then reached her fourth final of the year in Korea, falling to Radwanska in three sets.

This will be her second appearance at the event, but she will be hoping to fare much better this time, after she was heavily thrashed by Ana Ivanovic in her first appearance in 2010.

Alize Cornet
Current world ranking: 27
Titles this year: Strasbourg

2013 Grand Slam results
Australian Open: Second round
French Open: Third round
Wimbledon: Third round
US Open: Third round

Tournament of Champions history
Tournament debut
Best result: N/A
Last year’s result: N/A

After languishing outside the Top 30 for many years, this year will go down as the one in which Alize Cornet finally started realising her potential.

Her Grand Slam results weren’t as good as they should be, but she still reached the third round at all but one of the Slams this year – the blot being at the Australian Open where she lost to a resurgent Venus Williams in the second round.

The most disappointing result came at Wimbledon, where, in the third round, she bageled Flavia Pennetta and held a match point in the second set tiebreak before capitulating in three sets.

At the other two Slams, she won the first set against Victoria Azarenka before losing in three sets.

Now though, she remains France’s biggest hope of future success following the shock retirement of Marion Bartoli in August. So the pressure will be on her to deliver for the nation in the years to come.

Tsvetana Pironkova
Current world ranking: 106
Titles this year: None (wild-card entry)

2013 Grand Slam results
Australian Open: First round
French Open: First round
Wimbledon: Fourth round
US Open: First round

Tournament of Champions history
Second wild-card entry
Best result: Semi-finals (2012)
Last year’s result: Semi-finals

The Tsvetana Pironkova that we are seeing now is a distant shadow of the one that reached the semi-finals at Wimbledon three years ago.

This year has been one of massive disappointment for the 26-year-old, not winning any titles and only reaching two quarter-finals all year, at Hobart and ‘s-Hertogenbosch.

She was, however, able to reach the fourth round at Wimbledon, taking the first set off Agnieszka Radwanska before surrendering in three sets.

She will have the support of the home crowd once again, as she tries to follow up on her semi-final run from last year. The question will be, though, whether she can go one step further and reach her first final of the year.

So there we have it – but as nine women have been previewed, one will have to miss out.

As the lowest-ranked of the six direct qualifiers, Alize Cornet will be the one to miss out if Caroline Wozniacki is not required in Istanbul.

Lucie Safarova, formerly a quarter-finalist at the 2007 Australian Open, had qualified by winning in Quebec City, but she was pushed out of the qualification zone due to Wozniacki winning in Luxembourg last week.

The situation is very tricky given the Dane is the highest ranked of the alternates, so will be given first priority over Sloane Stephens, the second alternate in the Turkish city.

The rules appear to have changed this year so that if one player qualifies for both the Tour Championships and the Tournament of Champions, she can only play in one. Wozniacki finds herself in this situation as we speak.

Marion Bartoli remains the only player to play in both tournaments in the same year in 2011. That year, she filled in for Maria Sharapova in Istanbul after the Russian withdrew due to an ankle injury.

Like the Tour Championships, this tournament will employ a round robin format, and the standard rules will apply: the top two seeds from each of the two pools will move to the semi-finals, while the bottom two get eliminated and their season is over.

It’s set to be a thrilling end to the 2013 WTA season and with the strongest line-up in its five-year history, the Tournament of Champions will be one interesting tournament to end the year.