There are only two days remaining in the 2008 US Open, but by the time they’re over we’ll know a lot more about the new balance of power in both the men’s and women’s games.

The stakes have been raised in the men’s singles by the fact that the four semi finalists are also the world’s four best players.

The big three – Nadal, Federer and Djokovic – are there.

The fourth semi-finalist, Andy Murray, is ranked 6th in the world, but his potential has long been recognised and he seems finally ready to march past the 4th and 5th ranked players David Ferrer and Nikolay Davydenko.

Murray faces Nadal for a spot in the final.

Many will remember the match between these two in the 2007 Australian Open. Nadal won in five sets, but the Scot played a smart game, mixing his shots up, and varying pace and depth, which prevented Nadal from hitting his stride.

They’ve now faced each other five times and Murray is yet to chalk up a win. But it’s been a long, tough year for Nadal – the more you win, the more matches you play – and the slightest slip up will open the door to his precocious opponent.

Nadal will need to be at his best.

The other semi pits Federer against Djokovic, and what a momentous match this is for both players. If Federer wins, he proves he still has it and he can go into the final confident that, having beaten Djokovic, he has an edge as he vies for his 5th straight U.S. Open title.

If he gets to play Nadal in yet another grand slam final, it’s a chance to add another chapter in what is one of tennis history’s great rivalries and he will feel that, on a hard court, he has a real chance to turn the tide back in his favour after the French and Wimbledon disappointments.

If Djokovic wins, a real case can be made that Federer at present is no better than the third best player in the world.

On form, this is the most likely scenario.

Federer has not yet returned to his best after a battle with illness and the shattering mental blow of losing the epic Wimbledon final. And it remains to be seen if he can do so.

Djokovic has already beaten him in this year’s Australian Open and the Serb is at his best on this surface. He has shown signs of tiredness and injury during the course of the tournament but with Djokovic it’s hard to know if it’s all part of the show.

He has a war-like approach to the game and will do whatever it takes to get an advantage or fire himself up. His quarter-final dismissal of Roddick in a kind of grudge match seemed to indicate he is fully fit.

If Djokovic beats Federer, he will relish the opportunity to beat Nadal, and in so doing split the years Grand Slam titles at two apiece.

It would reinforce his claim to be the world’s best hardcourter.

The retirement of Justine Henin from the number one spot left a vacuum at the top of women’s tennis. There was no standout successor and the likes of Ana Ivanovic, Jelena Jankovic, Svetlana Kuznetsova and the currently injured Maria Sharapova all have claims on the spot, while Olympic finalists Safina and Dementieva snap at their heels.

However, the question has to be asked whether, in the absence of a clearly dominant player or two, the Williams sisters are still the best two players in the world when focused.

Despite the fact that they are now entering their late twenties and that their careers have suffered disruptions of all kinds, it seems that the only player who can beat a Williams sister who is fit and out there to win is another Williams sister.

The closest match Serena has had on her way to the final against 2nd ranked Jankovic was against Venus, which she won 7/6 7/6.

Serena has now brought her ranking back up to number three after being as low as the nineties in 2006.

One wonders if it’s only a matter of time before she reclaims the top spot. The way in which she deals with Jankovic should tell us a lot about that.

Enjoy sports? Enjoy a bargain? All Sports Online has your favourite sporting brands at up to 70% off. Online only, premium quality sporting goods and merchandise at discounted prices. Get a deal now.