A Monday men's final is becoming a U.S. Open tradition.

When No. 3 seed Venus Williams and No. 6 seed Francesca Schiavone meet up in the U.S. Open quarterfinals, someone will be losing their first set of the tournament.

Petra Kvitova knocked the No. 1 seed out in the third round at last year's U.S. Open, but upsetting No. 2 seed Kim Clijsters in 2010 will be more of a challenge.

Just a few months ago very few people would have brought up Mardy Fish, David Nalbandian or Marcos Baghdatis as being any real threat to surprise the field with deep U.S. Open runs. But their summer performances have made them U.S. Open sleepers to watch.

Tennis returns to New York with a number of interesting Day 1 storylines: America's sweetheart Melanie Oudin is back in action, Kim Clijsters is starting her title defense, Roger Federer is looking to make a run to reclaim his title and more. Take a look at five matches to watch.

Caroline Wozniacki of Denmark was seeded No. 1 at a Grand Slam tournament for the first time Tuesday, getting the top spot at the U.S. Open because Serena Williams pulled out with a foot injury.

Defending champion Juan Martin del Potro withdrew from the U.S. Open on Saturday, saying he "cannot compete at the top level yet" after having an operation on his right wrist in May.

A person familiar with Juan Martin del Potro's plans tells The Associated Press that the 2009 U.S. Open champion will not defend his title at the year's last Grand Slam tournament.

Rafael Nadal will return to Queen's this year after he was unable to defend his title at the grass-court tournament in 2009.