MELBOURNE, Australia — Serena Williams returned to No. 1 in the world rankings for the third time in her career following her Australian Open win, and Fernando Verdasco broke into the men's top 10 for the first time after advancing to the semifinals.

Williams spent four weeks atop the rankings after winning last year's U.S. Open. Her first stint at No. 1 started in July 2002 and lasted 57 weeks.

Verdasco moved to ninth in the projected rankings issued by the ATP after the tournament. If he had received extra points for court time, he might have improved even more from his 12th ranking two weeks ago.

Verdasco lost a 5-hour, 14-minute five-set marathon to fellow Spanish left-hander Rafael Nadal, breaking the previous longest-match record by three minutes.

No. 1 Nadal increased his lead over second-ranked Roger Federer after a five-set win over the Swiss star in the final on Sunday.

Nadal, who took over the No. 1 ranking from Federer last Aug. 18, will begin his 25th week at the top on Monday. With his Australian Open win, Nadal extended his lead over Federer to more than 3,000 points in the ATP rankings.

Novak Djokovic, who won last year's Australian Open final but lost in the quarterfinals to Andy Roddick this year, remains at No. 3. Britain's Andy Murray, who lost to Verdasco in the fourth round, stays at No. 4.

Nikolay Davydenko of Russia, who did not play the Australian Open due to a heel injury, held his place at 5.

Roddick, who lost to Federer in the Australian Open semifinals, jumped up three spots from 9 to 6, with Juan Martin del Potro, Gilles Simon, Verdasco and David Nalbandian rounding out the top 10.

Williams' 6-0, 6-3 win over Dinara Safina gave her the top women's ranking.

The 27-year-old American said No. 1 wasn't foremost on her mind.

"I actually forgot until the end when I was saying 'Hi' to my (players') box," Williams said. "They said 'Hey, you're No. 1.' I was like, 'Oh, yeah."

Safina's run to the final earned her the No. 2 spot. Jelena Jankovic dropped from No. 1 to No. 3, followed by Russians Elena Dementieva and Vera Zvonareva.

Serena's sister, Venus, is 6, followed by former U.S. Open winner Svetlana Kuznetsova of Russia and Ana Ivanovic of Serbia.

Agnieszka Radwanska of Poland and Nadia Petrova of Russia round out the top 10, each having moved up one spot.