By Nick Georgandis

WTA
Only in the perfectly nonsensical world of the professional tennis tour's ranking systems does the No. 2 player in the world lose to the No. 1 player in the world, and pass that No. 1 player in the rankings, even though the No. 1 player has not lost a single match this season and has won the two biggest tournaments.

So congratulations, Serena Williams, and tough break, Victoria Azarenka - try harder next time, except that you can't try harder when you're 14-0. But because of Williams' limited playing schedule in early 2012, the American legend reclaimed the No. 1 spot in the world for the first time since September of 2010 on Monday, even after losing to previous No. 1 Azarenka in the finals at Dubai on Saturday.

At 31 years old, Williams becomes the oldest woman to ever hold the No. 1 spot, surpassing Chris Evert in that regard. It also marks her 124th week to hold the position. She's sixth all-time in that category, but well out of the Top 5, which begins with Monica Seles at No. 5 with 178 weeks atop the charts. Williams is one of eight American women to have been ranked No. 1 during the Open Era, the most of any country. American women have held the top spot for 928 weeks in all, easily the most of any nationality. The second-highest total is Germany with 377 weeks, all of that from Steffi Graf.

The move up was less dramatic, but American Sloane Stephens moved up to No. 16 from No. 17, a new career high for the phenom who will turn 20 in a month. Also making a move inside the Top 20 was Ekaterina Makarova, who moved up a spot to 19th after reaching the second round at Doha, tying her career-best rank.

ATP
Despite winning the title at San Jose, Milos Raonic slipped back a spot in the rankings this week, falling to No. 14 behind Gilles Simon.

Other changes in the "teens" of the ATP rankings included the ageless Tommy Haas rising four sports to No. 18 in the world. Haas, who will turn 35 in a month's time, reached the finals at San Jose, upsetting American John Isner in the semifinals, to rejoin the Top 20 for the first time since May of 2010. Among those he surpassed in making the move was American Sam Querrey, who fell a spot to 21st after three straight weeks at No. 20.