Switzerland’s Roger Federer returns the

Roger Federer's mastery of the grass continued in Thursday's semifinals. (Martin Bernetti/AFP/Getty Images)

Roger Federer’s mastery of the grass continued in Thursday’s semifinals. (Martin Bernetti/AFP/Getty Images)

Switzerland’s Roger Federer returns the ball against Uzbekistan’s Denis Istomin during their men’s singles third round tennis match during the 2012 London Olympic Games at the All England Tennis Club in Wimbledon, southwest London, on August 1, 2012. AFP PHOTO / MARTIN BERNETTIMARTIN BERNETTI/AFP/GettyImages