Tennis | Roger Federer's ranking in danger

MASON, Ohio — Roger Federer lost another match and, perhaps, his longtime grip on No. 1, as well.

The world's top-ranked player had another out-of-character setback on Thursday, a three-set loss to Ivo Karlovic that left the Croat exulting on his back and opened the way for Rafael Nadal to take over the No. 1 spot by winning the Cincinnati Masters championship.

Nadal stayed on course for the seismic shift by beating Tommy Haas 6-4, 7-6 (7-0) later Thursday, reaching the quarterfinals with his 31st consecutive win. Three more wins and the top spot in the world rankings belongs to him next week.

Even if he doesn't win the championship in Cincinnati, he can pile up enough points to overtake Federer in the next few weeks.

"I know I'm in good position," Nadal said. "In truth, I don't think about it too much."

It's been a long time coming.

Federer has been ranked No. 1 since Feb. 2, 2004, a record of 235 consecutive weeks. He and Nadal have held the top two spots since July 25, 2005. They will swap if Nadal extends his run of five consecutive tournament titles.

Asked about the possibility, Federer said, "I don't care."

He's got bigger concerns.

Since his epic five-set loss to Nadal at Wimbledon, Federer has lost in the second round in Toronto and failed to make the quarterfinals in Cincinnati, where he won the title last year. The 26-year-old Swiss star has been struggling to regain his aura of domination since he started the year with mononucleosis.

Nadal has taken advantage by improving his hard-court game and surpassing Federer on the court if not in the rankings.

"Look, he's doing well and I have done well in the past," Federer said. "This year was hard, I guess, with the start of the year. But nevertheless, I still think it's been a good year. I just hope I can show it now at the Olympics and the U.S. Open."