Roger Federer celebrates a point during his match against David Ferrer.
© Clive Brunskill/Getty Images
LONDON (AP) -- On an indoor court, Roger Federer can win even when he's not playing his best.
He proved that again Thursday at the ATP finals, beating David Ferrer 6-4, 7-6 (5) and advancing to the semifinals with a match to spare despite struggling with his serve and scrambling to stay in long rallies.
Federer, a six-time champion at the season-ending event for the top eight players in the world, made only 53 percent of his first serves at the O2 Arena. And in his first two service games alone, he was forced to save six break points.
But he did save them, and three others, while getting broken only once.
With the victory, Federer improved his record over Ferrer to 14-0. In 10 years of facing each other, Ferrer has won only three sets against the 17-time Grand Slam champion.
That looked like it was going to change on Thursday.
The retriever Ferrer got to ball after ball to extend the rallies and keep Federer on the move. In the opening game, the Spaniard quickly took a 0-40 lead but failed to convert any of his three break chances.
He had three more chances in the third game - minutes after Federer had broken Ferrer's serve - but again Federer was able to hold.
Ferrer did finally manage a break to get back on serve at 3-2, but Federer didn't allow another.
Federer is 2-0 in the ATP finals, putting him into the semifinals. However, he still has to face Juan Martin del Potro on Saturday.
Del Potro will play Janko Tipsarevic in the other Group B match later Thursday. Ferrer and Tipsarevic will meet on Saturday.