French Open preview: Men's draw most open in years.

Injuries to top ranked players and stunning form from some of the lower-ranked players have made the lead up to Paris most intriguing. Picking this year’s champion is a very difficult task.

Rafael Nadal has taken up residence on court Philipp Chartrier since 2005 and has won seven of the last eight opens. For the first time since his reign began, however, he will not enter the tournament as the clear cut favourite.

He showed solid form in his return on the South American clay, then on the hard-courts of the USA after his six month injury layoff.

It was obvious, though, that long, strenuous matches still punish his troublesome knees.

Nadal withdrew from the Miami Masters after winning at Indian Wells in March to rest his knees in readiness for his beloved spring clay-court season.

Nadal surrendered his unbeaten crown at Monte Carlo to world number one Djokovic two weeks ago.

Federer’s surprise loss to Kai Nishikori in Madrid has done not only his French Open preparation some damage but also his ranking. He could slip to number three as he will lose considerable points for not being able to defend his Madrid title.

The monkey on Roger Federer’s back was always the French Open until his win in 2009. Always slightly vulnerable on clay, Federer surprised many in the lead up to the 2012 French Open with his win in Madrid.

Nadal criticised the new blue clay as being very fast and slippery in his defeat, so perhaps we cannot use this win as a true indicator of Federer’s ability to win on clay.

The French Open has always seemed to be more of a test of Federer’s patience than his ability. However, his reduced tournament schedule of 2013 may help him arrive in Paris as fresh and eager as ever. Realistically, this is his last genuine shot at the title.

It is difficult to assess the chances of world number three Andy Murray. He rose to number two briefly on the back of his Miami win, but his form since then has been underwhelming.

Like Federer it appears to be his patience on the slow clay that has let him down in the past.

World number one Djokovic proved at Monte Carlo that he has the measure of Nadal on clay, but it is his troublesome ankle that will be his biggest threat.

Djokovic first badly twisted it during the Davis Cup match against USA in April, and again in his match this week against Dimitrov.

Two weeks of long matches on clay could take its toll in Paris, where fitness is such a must-have weapon.

While it is difficult to go past the big four, there will be some worthy dark horses to contend with lurking in the draw.

Stanislav Wawrinka, who won in Barcelona, showed that his near upset of the world number one at the Australian Open was no one-off. The Swiss number two is dangerous on any surface.

Bulgarian Grigor Dimitrov, who caused a sensational second round defeat of Novak Djokovich this week, is blossoming into a big time contender in all tournaments.

Blessed with a stunning single-handed backhand equal of that of Federer, Gasquet or Wawrinka, he is a big threat. A kind draw could see him go deep into the second week.

Ditto the comeback kid, German Tommy Haas. The grand veteran is moving around the court with the ease of someone 15 years his junior. Self-belief does not seem to be a worry either, after he came back from 5-2 and set points down against Tommy Robredo in Madrid.

Apart from Nadal there is a bastion of Spanish conquerors, led by world number four David Ferrer, ready to grind it out for long hours to get through matches. These are names that no players want to see next to their own in the draw.

Australia’s male chances are sparse on Parisian clay, although Marinko Matosevic has showed some stellar form on the hard-courts so far in 2013.

Bernard Tomic will be just glad to be playing tennis and making that the focus of his life in the wake of all his off-court dramas.

The French Open runs from May 21 – June 2, at the Stade Roland Garros. Paris.