Roger Federer of Switzerland celebrates victory after the men's singles semifinal match against Andy Murray of Great Britain on day 7 of the ATP World Tour Finals in London, Britain, on Nov. 11, 2012. Federer won 2-0. (Xinhua/Yin Gang)

Roger Federer of Switzerland serves during the men's singles semifinal match against Andy Murray of Great Britain on day 7 of the ATP World Tour Finals in London, Britain, on Nov. 11, 2012. Federer won 2-0. (Xinhua/Tang Shi)

Roger Federer of Switzerland greets the spectators after the men's singles semifinal match against Andy Murray of Great Britain on day 7 of the ATP World Tour Finals in London, Britain, on Nov. 11, 2012. Federer won 2-0. (Xinhua/Wang Lili)

Roger Federer of Switzerland returns the ball during the men's singles semifinal match against Andy Murray of Great Britain on day 7 of the ATP World Tour Finals in London, Britain, on Nov. 11, 2012. Federer won 2-0. (Xinhua/Yin Gang)

Roger Federer of Switzerland returns the ball during the men's singles semifinal match against Andy Murray of Great Britain on day 7 of the ATP World Tour Finals in London, Britain, on Nov. 11, 2012. Federer won 2-0. (Xinhua/Yin Gang)

Roger Federer of Switzerland returns the ball during the men's singles semifinal match against Andy Murray of Great Britain on day 7 of the ATP World Tour Finals in London, Britain, on Nov. 11, 2012. Federer won 2-0. (Xinhua/Wang Lili)

Roger Federer of Switzerland returns the ball during the men's singles semifinal match against Andy Murray of Great Britain on day 7 of the ATP World Tour Finals in London, Britain, on Nov. 11, 2012. Federer won 2-0. (Xinhua/Tang Shi)

Andy Murray of Great Britain returns the ball during the men's singles semifinal match against Roger Federer of Switzerland on day 7 of the ATP World Tour Finals in London, Britain, on November 11, 2012. Murray lost 0-2. (Xinhua/Yin Gang)