TENNIS:RAFAEL NADAL is three wins away from ending Roger Federer's record run atop the ATP tennis rankings.

Ivo Karlovic, the 16th seed from Croatia, beat Federer 7-6 (8-6), 4-6, 7-6 (7-5) in the third round of the Cincinnati Masters on Thursday night, while Nadal won 6-4, 7-6 (7-0) against Tommy Haas of Germany to extend a career-best winning streak.

Nadal, who beat Federer in five sets in July's Wimbledon championship match a month after topping him in straight sets to take his fourth straight French Open title, will end the Swiss player's 235-week stint as number one if he wins tomorrow's final in Cincinnati.

"Look, he's doing well and I have done well in the past," Federer said after losing for the first time without his serve being broken. "This year was hard."

Nadal, who has a 4-0 record against Federer this year and a 12-6 lead overall, extended his winning streak to 31 matches by ousting Haas. Unbeaten since May 7th, Nadal lost his only meeting with his next opponent, 89th-ranked Nicolas Lapentti of Ecuador. The match was five years ago, when Nadal was 18 and Lapentti was 27.

Federer, a 12-time Grand Slam champion, has held the top spot in the rankings since February 1st, 2004. He broke Jimmy Connors's 30-year-old record of 161 weeks atop the rankings in February 2007.

Federer will carry the Swiss flag at next Friday's Olympic Games opening ceremony in Beijing. Federer, who will be celebrating his 27th birthday on the day of the ceremony, also led out his country at the opening of the Athens Olympics four years ago. Federer suffered an upset against Czech Republic's Tomas Berdych early in the Athens tournament.

Should Federer fail to win the US Open in New York, it will be his first year without a Grand Slam title since 2002.