Busted Racquet looks at the six former WTA No. 1s who will be playing at the upcoming U.S. Open.

Venus Williams -- Weeks: 11 -- First time: Feb. 25, 2002 -- Last time: July 7, 2002

How long has it been since Venus was ranked No. 1? The last time she led the WTA rankings, Nelly's "Hot in Herre" topped the Billboard charts and "My Big Fat Greek Wedding" was still in movie theaters. For a player of such stature, her two reigns at the top were remarkably brief. She almost has twice as many career Grand Slam titles (21) as she does weeks at No. 1 (11). Venus enters this U.S. Open unseeded and a longshot to make any sort of run in New York. The last time she won the tournament was a decade ago.

Serena Williams -- Weeks: 123 -- First time: July 8, 2002 -- Last time: Oct. 10, 2010

The previous five No. 28 seeds at the U.S. Open were Alisa Kleybanova, Sybille Bammer, Katarina Srebotnik and Ai Sugiyama (twice). They combined for seven wins, exactly the total Serena Williams will need to win her fourth title in New York.

[Related: Looking at Serena Williams' road to a fourth title]

Oddsmakers think she'll do it; Serena is getting 11/8 odds to win the tournament. The next best odds belong to Petra Kvitova at 5/1.

Maria Sharapova -- Weeks: 17 -- First time: Aug. 22, 2005 -- Last time: June 8, 2008

If not for Serena, Sharapova would be in the same boat she was in June for the French Open: coming off a big tournament victory and entering a Grand Slam as a favorite. There's no tougher competitor on the WTA (except, again, for Serena). The big "what if" is always her serve. It didn't fail her in Cincinnati. Maybe Irene's winds will calm down Masha's ball toss.

Kim Clijsters -- Weeks: 20 -- First time: Aug. 11, 2003 -- Last time: Feb. 20, 2011

Out, abdominal injury.

Ana Ivanovic -- Weeks: 12 -- First time: June 9, 2008 -- Last time: Sept. 7, 2008

Ana Ivanovic's seeds at the U.S. Open, starting with her first appearance in 2004: None, 18, 16, 5, 1, 11, none, 16. Last year, when the Serb bottomed out at No. 63 in the rankings, there was no template for whether she'd be able to return to the form that helped her become a Grand Slam winner. Her run to the fourth-round at last year's Open (while unseeded) gave her the kickstart she needed. Now Ana has the tough part -- stabilizing her game -- out of the way. Can she start putting together back-to-back matches?

Jelena Jankovic -- Weeks: 18 -- First time: Aug. 11, 2008 -- Last time: Feb. 1, 2009

While Ivanovic and Dinara Safina would see their games fall apart after becoming No. 1, Jankovic was able to tread water through her slump. She won big tournaments in 2009 and 2010 (Indian Wells and Cincinnati, respectively) and hovered inside the top 10 until falling out this year. A potential quarterfinal with Serena at the U.S. Open could be a diva blockbuster. That's assuming Jankovic can handle her business in the early rounds and get past Francesca Schiavone in the fourth.

Dinara Safina -- Weeks: 26 -- First time: Apr. 20, 2009 -- Last time: Nov. 1, 2009

Out, back injury.

Caroline Wozniacki -- Weeks: 45 -- First time: Oct. 11, 2010 -- Last time: current

The 21-year-old Dane doesn't get the "do you deserve to be No. 1?" question as much anymore, mostly because everyone knows the answer. When's the last time a No. 1 seed entered a Grand Slam and was given less of a chance to win than Wozniacki at the U.S. Open? In theory, Caro's draw sets up well.

[Related: How will women's former No. 1s fare at the U.S. Open?]

The top seed in her part of the quarter is the struggling Svetlana Kuznetsova. The top seed in the bottom part of the draw is Li Na, whose game has disappeared since winning the French Open. Other than a gimpy Andrea Petkovic, it's a pretty thin quarter. Could Wozniacki make a run? Or is another early-round exit in the offing?

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