PARIS — Roger Federer lost three of his first four service games today, causing a stir among French Open fans but only briefly delaying his progress to the semifinals.

The top-ranked Federer rallied to defeat Fernando Gonzalez 2-6, 6-2, 6-3, 6-4 and reach the final four at his 16th consecutive Grand Slam event.

"It's always a great pleasure being in the last four," Federer said. "It's really where it gets most interesting."

Seeking the only major title he has yet to win, Federer next will face unseeded Frenchman Gael Monfils, who delighted a capacity crowd on center court by beating No. 5-seeded David Ferrer 6-3, 3-6, 6-3, 6-1. No. 2 Rafael Nadal, the three-time defending champion, will play No. 3 Novak Djokovic in the other semifinal Friday.

By this week's standards at Roland Garros, Federer's comeback against Gonzalez was modest. Dinara Safina came within a point of defeat for the second consecutive match, but made the semifinals by beating fellow Russian Elena Dementieva 4-6, 7-6 (5), 6-0.

The semifinal berth is the first in a major tournament for Safina, the younger sister of two-time Grand Slam champion Marat Safin. Her latest rally was remarkably similar to the one she mounted against top-ranked Maria Sharapova in the fourth round.

"Once you went through this you always believe, `Why not the second time?"' Safina said.

Her opponent Thursday will be another Russian, 2004 U.S. Open champion Svetlana Kuznetsova.

"Dinara is playing very well," Kuznetsova said. "She has too many lives, so I have to be careful with her."

Kuznetsova recovered from her own slow start to beat unseeded Kaia Kanepi 7-5, 6-2.

The other women's semifinal will be an all-Serbian match, with No. 2-seeded Ana Ivanovic playing No. 3 Jelena Jankovic.

Federer appeared susceptible to an upset after committing a dozen unforced errors in the first set, which he lost in 25 minutes. He found himself on the defensive against the No. 24-seeded Gonzalez, who came into the match 16-0 on clay this year.

"I was a bit afraid because the match was not going the way I wanted," Federer said. "I was really under pressure in the first set. I felt uncomfortable. I was missing a lot of shots, and he defended well."

Federer became more aggressive, attacking Gonzalez's forehand. The change in tactic helped him repeatedly reach the net, where he won 29 of 35 points.

In the final three sets, Federer held all 13 service games. He won 36 of his final 40 service points, including the last 17 in a row.

"I was really happy the way I came back," he said. "I really got on a roll, played great and was able to dominate him at times."

After closing out the victory with a drive volley, Federer raised a fist as he skipped on the clay — a rare display of exuberance from the Swiss champion. His 12 major titles are second only to Pete Sampras' 14, and he's bidding to become the sixth man to win all four Grand Slam championships.

Federer is 3-0 against Monfils, the first Frenchman to reach the final four at Roland Garros since Sebastien Grosjean in 2001. Monfils, who will play in his first major semifinal, was French Open boys champion in 2004.

The No. 13-seeded Safina trailed Dementieva 5-2 in the second set and faced a match point in the next game, but Dementieva dumped a return into the net. That triggered a sudden reversal, and Safina lost only one game the rest of the way.

The big-hitting Safina changed tactics when she fell behind, switching to a less aggressive approach. The strategy coaxed a flurry of errors from an increasingly flustered Dementieva.

"I changed my game completely," Safina said. "I think she got confused, because I wasn't hitting the ball anymore like I did in the first set. I was like, `OK, you have to hit winners."'

Safina won five consecutive games to climb back into the match, and Dementieva had to erase three set points in the next game to hold for 6-all.

In the tiebreaker, Dementieva committed three consecutive unforced errors to fall behind 6-3. On Safina's sixth set point, she skipped a backhand off the baseline for a winner to take the 80-minute set and even the match.

A dejected Dementieva gave away the final set, committing 15 unforced errors while winning only 14 points.

"It was very hard to play the third set after I had so many chances to finish the match," she said.

Kanepi, an Estonian playing in her first Grand Slam quarterfinal, was hurt by her own mistakes, too. She committed 31 unforced errors and lost 16 of 24 points on her second serve.

Still, Kanepi took an early lead.

"She started very well. She was hitting so hard," Kuznetsova said. "I showed her that I was tough, and so at some moments she started to miss more."

Kuznetsova lost serve to fall behind 4-2 when she ended an 11-stroke exchange by putting a forehand into the net. Kanepi raised a fist, bent over and yelled in excitement, while her supporters in the guest box stood and cheered while waving Estonian flags.

Kanepi went ahead 40-love in the next game, a point from a 5-2 lead, before her game unraveled. Kuznetsova won the next point, a 12-stroke rally, with a forehand winner, and Kanepi dropped the next four points too, all on her miscues, capped by a double-fault on break point.

That began a run in which Kuznetsova won five of six games — and 23 of 32 points — to take the first set.

She raced to a 5-1 lead in the second set, and after closing out the victory with a forehand winner, she waved a clenched fist as she walked to the net.