PARIS — There have been times this year when Roger Federer’s cloak of infallibility slid from his shoulders, when his absolute dominance against anyone but Rafael Nadal and at any tournament but the French Open wasn’t quite so absolute.

Federer arrived at Roland Garros with one title, his lowest count since 2001. He arrived with seven losses, more than his total for any of the previous three entire seasons.

And so it was yesterday that for the first set of his French Open quarterfinal against 24th-seeded Fernando Gonzalez, Federer looked, well, human. His serve was broken three times. He shanked shots. He was, by his own admission, “a little bit rattled.”

Still, as he’s done so many times, Federer adjusted and regrouped, beating Gonzalez 2-6, 6-2, 6-3, 6-4 to extend his own record by reaching a 16th consecutive Grand Slam semifinal. Federer moved two wins away from completing a career Slam and earning his 13th major championship, which would leave him one shy of Pete Sampras’ mark.

“At one stage, I was a bit afraid,” the no. 1-ranked Federer said, “because the match was not going the way I wanted.”

Impressive as it was, Federer’s turnaround had nothing on the one fashioned yesterday by no. 13-seeded Dinara Safina in the women’s quarterfinals. The younger sister of two-time major champion Marat Safin trailed no. 7 Elena Dementieva by a set and 5-2 in the second, then was one point from losing at 5-3, before coming all the way back to win 4-6, 7-6 (5), 6-0.

The deficit was identical to the one faced by Safina a round earlier, when she trailed by a set and 5-2 in the second, and erased a match point at 5-3, en route to upsetting no. 1 Maria Sharapova.

“Once you went through this,” Safina said, “you always believe: ‘Why not the second time?'”

Safina’s semifinal today will be an all-Russian matchup against no. 4 Svetlana Kuznetsova, the 2004 U.S. Open champion and 2006 French Open runner-up. No. 2 Ana Ivanovic and no. 3 Jelena Jankovic will meet in an all-Serbian semifinal.

Kuznetsova, who defeated Kaia Kanepi of Estonia 7-5, 6-2, took note of Safina’s last two performances.

“She has too many lives,” Kuznetsova said, “so I have to be careful.”

Safina looked quite a bit like her brother between points, throwing mini-tantrums, including when she whacked some courtside geraniums with her racket, scattering red petals.

She handed Dementieva a match point at 5-3 in the second set by double-faulting to 30-40.

“I just choked so badly,” Safina said.

Dementieva repaid the favor, though, by flubbing a backhand return. Later in that set, Safina wasted five set points — three at 6-5, two in the tiebreaker — before finally converting on her sixth with a backhand winner that caught the baseline.

The final set was no contest, allowing Safina to reach her first major semifinal.

“You can say that it’s a breakthrough,” she said.

On Friday, Federer faces 59th-ranked Gael Monfils, a 21-year-old Frenchman who is the lowest-ranked semifinalist in Paris since 1999. It’s Monfils’s first Grand Slam semifinal.

“I’m at home,” Monfils said after delighting local fans by knocking off no. 5 David Ferrer 6-3, 3-6, 6-3, 6-1. “I’m ready and waiting for him.”

In Friday’s other match, three-time defending champion Nadal will take a 26-0 record at the French Open into his showdown with no. 3 Novak Djokovic, the Australian Open winner.