I'm Going to TennisWorld! - Clue #2

Okay, folks, here's the second clue to the Tennis Magazine U.S. Open Trivia Challenge (see my previous posts, starting with I'm Going to TennisWorld!, for details):

The U.S. has a long and distinguished tradition in doubles. This doubles team lost in third round of the biggest title won by the best Open-era player out of Switzerland before Roger Federer.

Please submit your answers to TennisWorld@tennismagazine.com

No other form of entry will be accepted. You may enter as often as you like. Good luck!