Serena Williams became the first player to clinch a spot in the semifinals of the WTA Sony Ericsson Championships yesterday at Doha, Qatar, defeating Elena Dementieva, 6-2, 6-4, for her third straight win in the tournament's round-robin group phase.

Her sister Venus, the defending champion, stayed alive by beating Svetlana Kuznetsova, 6-2, 6-7 (3), 6-4, for her first win in three matches. She needs Kuznetsova to beat Dementieva today to have a chance of advancing to the semifinals.

Earlier, Caroline Wozniacki overcame severe leg cramps to beat Vera Zvonareva, 6-0, 6-7 (3), 6-4.

After the match, Zvonareva, who replaced the injured No. 1 Dinara Safina on Wednesday, pulled out of the tournament citing a right ankle injury. Her place will be taken by the second alternate, Agnieszka Radwanska of Poland. She will play Victoria Azarenka today but has no chance of advancing.

Serena Williams, who secured the year-end No. 1 ranking when Safina retired with a back injury, has failed to get out of the round-robin phase of the elite tournament for the last two years.

"I'm happy to finally do well," she said. "I'm kind of used to the elimination thing: If you lose, you're out. But I was just trying to do better than I did last year, and compete in all my matches, which sometimes is very hard."

BOXING

MAYWEATHER WON'T FIGHT, SAYS PACQUIAO

Manny Pacquiao believes the biggest potential fight in boxing will never happen because Floyd Mayweather Jr. wants no part of him.

Pacquiao is training in Hollywood for his meeting with Miguel Cotto on Nov. 14, but the pound-for-pound champion said yesterday that his chance of fighting pay-per-view king Mayweather in what would be an extremely lucrative bout for both fighters is slim.

"I don't think it's going to happen," Pacquiao says. "I'm sure he doesn't want to fight.

"Boxing for him is like a business. He doesn't care about the people around him watching. He doesn't care if the fight is boring, as long as the fight is finished and he gets (plenty of) money. ... I want people to be happy. You have a big responsibility as a boxer."

COLLEGE FOOTBALL

TAR HEELS KICK PAST NO. 14 HOKIES, 20-17

Casey Barth kicked a 21-yard field goal on the final play as North Carolina upset No. 14 Virginia Tech, 20-17, last night at Blacksburg, Va.

The Tar Heels (5-4, 1-3 Atlantic Coast Conference) forced a fumble by Ryan Williams at his own 24 with 2:02 left and turned it into the winning drive.

The Hokies (5-3, 3-2), who until losing to No. 11 Georgia Tech 12 days ago were in the national championship picture, lost their second straight.

AND WHAT'S MORE ...

Phil Blackmar and Jeff Sluman shot 6-under 66s in breezy conditions yesterday to share the first-round lead in the Champions Tour's season-ending Charles Schwab Cup Championship at Sonoma, Calif. ... The first round of the PGA Tour's Viking Classic at Madison, Miss., has been postponed until today after steady overnight rain and the chance for more kept golfers off the course yesterday. ... American Anthony Kim won two round-round robin matches in the Volvo World Match Play Championship, while fourth-ranked Paul Casey lost twice to drop out of contention for a semifinal spot at Casares, Spain. ... Abby Wambach scored in the 34th minute to lift the United States women's national soccer team to a 1-0 victory over world champion Germany in yesterday's friendly before a crowd of 28,367 at Ausgburg, Germany.