Del Potro beats Federer to reach semis in London

LONDON (AP) - Juan Martin del Potro clinched the last spot in the semifinals of the ATP finals on Saturday, beating Roger Federer 7-6 (3), 4-6, 6-3 in their final round-robin match.

Federer had already qualified for the semifinal. Both players finished the group stage with 2-1 records.

Del Potro's win leaves David Ferrer and Janko Tipsarevic with nothing but prize money to play for in their final group-stage match. However, that result will still decide whether Federer or Del Potro finishes top of Group B and will therefore impact the semifinal matchups at the season-ending event.

The winner of the group will face Andy Murray on Sunday, while the second-place finisher plays top-ranked Novak Djokovic.

Del Potro converted his only break point of the match in the opening game of the deciding set and then held his own serve comfortably to wrap up the win at London's O2 Arena.