LONDON, ENGLAND - AUGUST 03: Roger Federer of Switzerland celebrates his 4-6, 7-6, 19-17 win over Juan Martin Del Potro of Argentina in the Semifinal of Men's Singles Tennis on Day 7 of the London 2012 Olympic Games at Wimbledon on August 3, 2012 in London, England. (Photo by Clive Brunskill/Getty Images)
LONDON, ENGLAND - AUGUST 03: Roger Federer of Switzerland celebrates his 4-6, 7-6, 19-17 win over Juan Martin Del Potro of Argentina in the Semifinal of Men's Singles Tennis on Day 7 of the London 2012 Olympic Games at Wimbledon on August 3, 2012 in London, England. (Photo by Clive Brunskill/Getty Images)