Dudi Sela jumped 19 places to number 87 in the ATP rankings on Monday after reaching the third round of the Australian Open last week. The 23-year-old Israeli will play in the SA Tennis Open in Johannesburg this week and faces a very tough opponent in the first round after being drawn to play world No. 13 David Ferrer. Shahar Pe'er's first round loss at the Australian Open cost her six places in the WTA rankings, with the Israeli falling to No. 48 in the world. Pe'er and Tzipi Obziler, who moved up 11 places to No. 166, will lead Israel's Fed Cup team in its World Group II tie at Ukraine this coming weekend. Serena Williams' return to No. 1 was the most notable move in world rankings following her Australian Open win, but a Spanish left-hander not named Rafael Nadal made a significant jump. Williams rose to No. 1 for the third time in her career - her first 57-week stint started in July 2002 and she spent another four weeks atop after winning last year's US Open. Fernando Verdasco moved into the men's top 10 for the first time after making it to the Australian Open semifinals. If Verdasco, who moved to ninth, got extra points for length of time on court, 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 leftie Nadal in the semifinals, 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 August 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, with Britain's Andy Murray, who lost to Verdasco in the fourth round, remaining at No. 4. Roddick, who lost to Federer in the Australian Open semifinals, jumped up three spots from 9 to 6. 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.