Wimbledon champion Serena Williams officially moved up to No. 1 in the WTA Tour rankings, the first time she's been ahead of older sister Venus. The 20-year-old Serena is the 11th woman to lead the standings since 1975. She replaces Venus, who's had three stints at No. 1 for a total of 11 weeks since February.

It's the eighth change at the top this year.

Serena has won the last two Grand Slam tournaments, beating her sister in the finals of Wimbledon on Saturday and the French Open last month. She's 36-3 with a tour-leading five titles in 2002, and is currently on a season-high 19-match winning streak, reported The Associated Press.

In the men's rankings, Wimbledon winner Lleyton Hewitt strengthened his hold on No. 1, while Pete Sampras, who lost in the second round at the All England Club, dropped three spots to 16th. A six-time year-end No. 1, Sampras hasn't finished a season out of the top 10 since 1989, his second as a pro.

Three-time major champion Jennifer Capriati, who lost her No. 1 ranking after Roland Garros, stays at No. 3 this week, followed by Monica Seles, Kim Clijsters, Jelena Dokic, and Justine Henin.

Martina Hingis slid to eighth, with Lindsay Davenport ninth and Wimbledon semifinalist Amelie Mauresmo 10th.

Hewitt is followed by Marat Safin, Tommy Haas, Wimbledon semifinalist Tim Henman and Yevgeny Kafelnikov.

Andre Agassi is the top U.S. player at No. 6, with French Open champion Alberto Costa seventh.

Hewitt also leads the ATP Champions Race. Safin is second in the race, followed by Henman, Costa and Agassi.