Federer defeat clears way for Nadal to reach top

Roger Federer's record 4-1/2 year reign as world number one could end this week after he was beaten 7-6 4-6 7-6 by Croatian Ivo Karlovic in the third round of the Cincinnati Masters on Thursday.

Spaniard Rafael Nadal, who beat Federer in this year's French Open and Wimbledon finals, will take over from the Swiss as the world's top ranked player if he wins the tournament tomorrow night.

The 2.08-metre tall Karlovic, who has hit more aces and won more service games than any other player on the ATP Tour this year, applied constant pressure.

Karlovic, who reeled off 22 aces and many more service winners, has also played more tiebreaks than anyone else this season, the potency of his delivery frequently reducing each set to a shoot-out over a dozen or so points at the end.

This was about the worst scenario for an already under-pressure Federer, who is still trying to recover from the biggest emotional setback of his career - the loss of his Wimbledon title to Nadal three and a half weeks ago - and whose confidence is at low levels.

"It's not easy coming from slower conditions to fast ones," Federer told reporters. "But I have played Ivo on all surfaces and he actually gets a greater play on the slower ones.

"But what are you going to do today if he serves like that? Maybe if I got the first set I would be sitting here and it would be different, but that's not the case."

Last week Federer lost his opening match in Toronto to unseeded Frenchman Gilles Simon and in Cincinnati he almost went out in his opener again, surviving against Robbie Ginepri only after the American was serving for the match.