...by Julian Finney/Getty Images) Serbia's Novak Djokovic returns the ball to Czech Republic's Radek Stepanek during the semi final match at the Swiss Indoors ATP tennis tournament on November 7, 2009...

Serbia's Novak Djokovic returns the ball to Czech Republic's Radek Stepanek (out of camera range) during their semi-final match at the Swiss Indoors ATP tennis tournament...

Novak Djokovic, of Serbia, reacts during the third set against Radek Stepanek, of the Czech Republic, during their match at the U.S. Open tennis tournament in New...

Serbian tennis player Novak Djokovic celebrates after winning against Czeck ' s Radek Stepanek, during day eight of the 2009 US Open at the USTA Billie Jean King National Tennis...

ROME - MAY 10: Novak Djokovic of Serbia in action before his apponent Radek Stepanek of the Czech Republic is forced to retire at the end of the first game of...

Radek Stepanek of the Czech Republic reacts after winning a game against Novak Djokovic of Serbia at the...

2007 U.S. OPEN

Novak Djokovic had reason to get excited after beating Radek Stepanek in a five-set match that lasted 4 hours, 44 minutes

Novak Djokovic of Serbia reacts after losing a point to Radek Stepanek of the Czech Republic at the US Open tennis tournament in New York, Friday, Aug. 31...