With the preliminaries now out of the way, the US Open men's competition can really begin.

As expected, the world's top four players, Novak Djokovic, Rafa Nadal, Roger Federer and Andy Murray, are safely through to the semi-finals. All are in fantastic touch and brimming with confidence and picking the eventual winner is no easier now than when the two-week tournament began.

Djokovic will play Federer in the first semi on the Arthur Ashe Stadium court while Nadal and Murray will lock horns in the second on a rare day when the big four all get together. "It's good for tennis," said Murray. "That's probably what people would like to see."

Normally, the two winners would meet in the final on Sunday but the championship has been pushed to Monday because two days were lost to rain, meaning Nadal or Murray will be forced to play four matches in four days.

Novak Djokovic started the tournament as the slight favourite after an incredible year in which he lost just two matches, including one to Federer, and captured grand slams title in Australia and at Wimbledon.

But the World No. 1 will have his work cut out just getting past Federer, already a five-time winner at Flushing Meadows. The Swiss master may be on the wrong side of 30 but he appears as fit as ever and has lost none of his wizardry and court-craft. Both have lost just one set en route to the semis and are very familiar with each other's games.

Roger Federer leads their head-to-head battles 14-9 and they have played each other at the US Open in each of the past five years. Federer won the first four times but Djokovic won last year and has gone to become the undisputed No. 1 player in the world this season.

"It's always a great matchup between the two of us. There is no real secrets out there," Federer said. "We have had particularly good matches here at the US Open, and I have the feeling it's going to be something similar again."

Murray's match against Nadal is also looming as a classic battle. The defending champion has a 12-4 advantage over Murray but the Scotsman beat him in the 2008 US Open semi-finals and the quarter-finals of this year's Australian Open.

"When I've won against him, it's always been on hard courts," Murray said. "It's a good surface for me to play him on.

"Obviously at the French I would go into that match not being a favourite; then Wimbledon I've got a chance, but his record has been great there. I think on the American hard courts I think it's a close, close matchup."

Murray and Nadal have not been as impressive as Djokovic and Federer in getting to the semis but both have displayed enough signs to show they can win the title.

Murray came from two sets down to win a second round match against Robin Haase while Nadal is the only player yet to drop a set.

"Even if I lose tomorrow, I am happy about my US Open," Nadal said. "It wasn't an easy situation for me coming to this tournament after not having an easy summer.

"I am doing a lot of things much better than few weeks ago. For me, a win is important but to feel competitive and have the feeling that I can win is probably even more important."

India's campaign at the US Open ended after the fifth seeded Indo-Pak pair of Rohan Bopanna and Aisam-ul-Haq Qureshi crashed out following a straight-set loss to the Polish pair of Marcin Matkowski and Maruisz Fyrstenberg in the men's double semi-final in New York. At the end of an 82-minute battle, the sixth-seed duo from Poland got the better of the Indo-Pak Express 6-2, 7-6, (7-4).