Roger Federer may have won the Australian Open earlier this year in dominant fashion - but there are signs that his campaign for a fourth successive US Open title won't be so smooth.

This year, Federer hasn't been as dominant on tour as he was in 2006. Rafael Nadal actually leads the ATP Tour champions' race. Aside from his Melbourne victory, Federer has exhibited a poor run of form on hard courts by his own stellar standards. In 2005 and 2006 he achieved the prestigious Indian Wells/Miami double but this year he crashed out early in both North American hard-court tourneys, losing to Guillermo Canas.

Nadal, meanwhile, ended his own title drought by taking the Indian Wells trophy. Losses to Andy Murray at Cincinnati last year and to Marat Safin at the 2005 Australian Open show that Federer can be vulnerable on hard courts and up-and-coming players such as Novak Djokovic, who captured Miami, the world's premier hard-court tournament after the Australian and US Opens,  will be eager to pounce on Federer in New York.

'While Federer's game works wonders on grass (as his five Wimbledon titles testify), he is prone to errors on slower surfaces due to his impatience'


While Federer's game works wonders on grass (as his five Wimbledon titles testify), he is prone to errors on slower surfaces due to his impatience -- a fact which dogged and determined players like Nadal and Canas use to their advantage all too well. The surface at the US Open is slower than that in Melbourne, which is obviously good news for Nadal.

The Spaniard's game, meanwhile, has matured in the past couple of years - along with his character. In his recent Wimbledon campaign and particularly in the final against Federer, he was frequently seen charging to the net and volleying. Nadal has thus shown that he is willing and able to adapt his play to get to the top, breaking away from the Spanish tennis tradition of excelling on slower surfaces but failing to thrive on faster ones.

Through a mixture of bad luck, injuries and poor form, Nadal has had disappointing results at the Australian and US Opens compared with the other two Slams. But his second consecutive run to the Wimbledon final shows that he is here to stay and is the main threat to Federer's rule, as does his hard-court victory over former US Open champion Andy Roddick earlier this year.

A strong US Open series and showing at Flushing Meadow from Nadal (who has few points to defend) could see the long-time world No.2 finally challenge for Federer's No.1 spot. A second successive run to the Wimbledon final proves that Nadal has what it takes to thrive on faster courts and arguably the Spaniard is closer to snatching Federer's Wimbledon title than the Swiss is to stealing Nadal's tight grip on the Roland Garros crown.

If Nadal can take Federer to five sets on grass, then his task of capturing his rival's other Grand Slam titles should be achievable.