That Federer lost the second set of his quarterfinal against No. 9-seeded Tommy Robredo of Spain qualified as a "Stop the presses!" moment — not only because Federer won his previous 36 Grand Slam sets to break an Open era record, but also because of the margin.

"I don't lose sets 6-1 that often, you know," Federer said, "so you're like, 'Oh, come on."'

Robredo looked at his mini-victory this way: "It was as if I had said, 'Hello! Wake up!"

That was certainly the effect the one-set slip-up had on Federer, who quickly returned to his customary level of play for a 7-5, 1-6, 6-1, 6-2 victory, reaching the semifinals at a record 12th major tournament in a row.

"In the second set, for some reason, I just couldn't really figure out how to play him or the way I want to play him," Federer said. "I didn't figure it out."

He started the third set poorly, too, missing a forehand wildly to fall behind 15-40 while serving the opening game. But Robredo then pushed a backhand into the net, and Federer was on his way, taking 17 of 19 points.

Federer wound up with a 26-5 edge in winners over the final two sets.

"He just started playing so good," said Robredo, who won his first career match against Federer back in 2002 but has lost the eight meetings since.

Now Federer takes on someone else he's dominated: No. 4 Nikolay Davydenko, who reached his second French Open semifinal by beating No. 19 Guillermo Canas of Argentina 7-5, 6-4, 6-4.

While Canas defeated Federer twice this season, Davydenko is 0-8 over his career against the Swiss star heading into Friday's semifinals.

"If Canas beat me today, Federer (would) have more trouble," Davydenko said. "Against me ... he has more confidence."

While Davydenko never has been to a Grand Slam final, Federer has a chance to play in his eighth in a row, something no man has done. And Federer, who already owns 10 major titles, is trying to become the first man since Rod Laver in 1969 to win four consecutive Grand Slam tournaments.

The other men's quarterfinals are Wednesday, when two-time defending champion Rafael Nadal plays 1998 champion Carlos Moya, and No. 6-seeded Novak Djokovic faces 125th-ranked Igor Andreev.

In his previous match, Federer tied two Open era records, with his 11th straight-set Grand Slam victory in a row and by running his consecutive-sets streak to 35. Both marks were established by John McEnroe at Wimbledon and the U.S. Open in 1984.

Until the second set today, Federer had not dropped a set at a major tournament since the second set of last year's U.S. Open final against Andy Roddick. Federer took the next two sets to claim that title, then won all seven of his matches at this year's Australian Open and his first four matches at the French Open in three sets.

But after taking the opener against Robredo, Federer had quite a lapse.

Missing all sorts of shots, some off his frame, Federer got broken at love to fall behind 2-0, and broken again to make it 5-1.

"Not looking for excuses, but you know, it was windy. And I didn't play well in that set, that's for sure," Federer said. "But he played solid. Didn't miss much. Used his forehand very well."

Federer also acknowledged a strategic error, saying he was "hitting too flat instead of looping the ball a bit more and using the wind."

Still, he made Robredo earn it, saving four set points before the Spaniard closed it.