Nikolay Davydenko, playing with a stress fracture and in the shadow of scandal, lost to unseeded Radek Stepanek 6-4, 7-5.

It is Federer's 10th consecutive win over the former world No. 1 since 2004. Federer will play Radek Stepanek in the semifinals.

Federer needed one service break to take the first set. He seemed ready to coast when Hewitt double-faulted on break point to open the second, but Hewitt broke back for 2-2, only to give back the advantage again two games later.

The fourth-seeded Davydenko rallied from 4-2 down in the second set. He broke serve to make it 5-5 before wasting a 40-15 lead and handing the advantage back to Stepanek, whose closed out the match on his serve.

Davydenko said this week he is playing with a stress fracture in his left foot. The injury caused him to withdraw from a controversial match with Martin Vassallo Arguello of Argentina last week at the Poland Open.

The ATP has started an investigation into possible match-fixing because of an irregular rush of betting on Arguello, ranked No. 87, on the online gambling site Betfair. Davydenko has denied any wrongdoing.