Federer, who won this event in 2005, will face the winner of the later match between fifth-seeded Nikolay Davydenko and ninth-seeded James Blake.

"I missed 50 last week by three or four points," Federer said of his loss in the Rogers Cup finals in Montreal to Novak Djokovic. "Maybe I'll get a little bit closer this week."

It was the second straight match in which the top-ranked player in the world was pressed to three sets. He beat Nicolas Almagro 6-3, 3-6, 6-2 on Friday.

"It was quite a fight. It was a good match, I thought," Federer said of his 20th match with Hewitt. "I think it was the best match I've played this week."

Federer and Hewitt exchanged service breaks in the second and third games before Federer broke Hewitt again in the fourth game with a blistering cross-court shot to take control of the first set.

Both players held throughout the second set, which Hewitt won in a tiebreaker.

The third set went much like the first, with Federer and Hewitt trading service breaks in the fifth and sixth games.

But the second tiebreaker was played much differently than the first, in which Hewitt won the first three points and ultimately prevailed. This time, Federer yielded only on Hewitt's first serve, then ran off six straight points.

"In the second-set tiebreak, I played the big points well, and in the third-set tiebreak, he played the big points well," Hewitt said.

Federer committed 36 unforced errors, but also served 18 aces.

"I thought I served really well," Federer said. "I'm very happy."

Federer has beaten Hewitt 11 straight times, including last week's quarterfinals in Montreal.

"The last two weeks have been good," Hewitt said. "Couldn't have asked for two better weeks, and it's taken the best guy in the world to knock me off."

Hewitt dominated Federer in their early matches, taking 7 of 9 from 1999 to 2003. But he has not beaten Federer since then.