Roger Federer of Switzerland plays a return to David Ferrer of Spain during their singles tennis match at the ATP World Tour Finals in London, Thursday, Nov. 8, 2012. (AP Photo/Kirsty Wigglesworth)

Associated Press
Roger Federer of Switzerland plays a return to David Ferrer of Spain during their singles tennis match at the ATP World Tour Finals in London, Thursday, Nov. 8, 2012. (AP Photo/Kirsty Wigglesworth)
Roger Federer of Switzerland plays a return to David Ferrer of Spain during their singles tennis match at the ATP World Tour Finals in London, Thursday, Nov. 8, 2012. (AP Photo/Kirsty Wigglesworth)