MOSCOW, November 10 (R-Sport) - Juan Martin Del Potro reached the semifinals of the ATP World Tour Finals on Saturday after the Argentine stunned world No. 2 Roger Federer.
Del Potro needed three sets to overcome his Swiss opponent 7-6(3), 4-6, 6-3.
Defending champion Federer had already qualified from Group B after winning his two opening matches.
World No. 1 Novak Djokovic and Andy Murray reached the semifinals from Group A on Friday.
David Ferrer plays Janko Tipsarevic later Saturday.
Neither can reach the semifinals, but the result of their encounter will determine which of Del Potro and Federer progresses as group winner.
