PARIS -- The stout breeze was ruffling Roger Federer's white shorts, and he was clearly uncomfortable on yawning Court Philippe Chatrier. When your game is as intricate as Swiss clockwork, when your hair is always just so, the wind can wreak havoc with all those moving parts.
Federer took a healthy backhand cut, and the ball, moving like a knuckler, glanced off the top of his frame and very nearly disappeared. Soaring in a huge parabola, it had a hang time of about four seconds and wound up in the box seats, sending the fedora-wearing aristocrats scattering.
Thus, Gael Monfils -- a bit of a knuckleball himself -- took a 3-1 lead on Federer in their quarterfinal match. The French star, "Le Monf," is a notorious front-runner. He usually plays well in his home Grand Slam and feeds off the love and hopes of his countrymen. But -- and there always seems to be a "but" -- for all his athletic gifts, he is given to a wandering, wavering attention span.
Inevitably, the moment came, courtesy of a Monfils lapse. Federer seized it, and like that shank that touched the clouds, he was gone.
Federer defeated Monfils in an extraordinarily breezy match, 6-4, 6-3 7-6 (3). Through five matches, the Swiss has yet to drop a set and arrives in his hoped-for semifinal match against Novak Djokovic in a terrific frame of mind.
"I'm very happy, and I'm feeling very good," Federer said. "I'm proud of the achievement. Novak and Rafa [Nadal] and I all had tricky draws, so I'm happy that I made my way through to the semis."
Federer and Monfils combined for 95 unforced errors, an unusually high number for a three-set match. At one point, the Frenchman was about six feet from the net and contrived to hit an overhead -- straight into the ground short of the net.
"I had occasions; I had opportunities," Monfils said. "But he was stronger than I was."
So in the end, they were who we thought they were.
Monfils is a talented but ultimately flawed player whose three career titles came at Montpellier, Metz and Sopot (a prize for those geography geeks who can guess which countries those prestigious events were in). He won his first four matches at Roland Garros -- his longest win streak of the season -- but he has lost to Federer here three of the past four years.
Federer, meanwhile, continues to be Federer -- when he isn't playing Djokovic or Nadal. Although Monfils' best effort in a major is reaching the semifinals here in 2008 (when he lost to … guess who), Federer has made the French Open final four in six of the past seven years.
In four of those semis, Federer lost to Nadal, a five-time title holder. On Friday he'll meet Djokovic, who has started the 2011 season by winning his first 41 matches. Three of those wins were over Federer, but all on the quicker hard courts.
If Djokovic wins, he'll become the No. 1 player among ATP World Tour players. How badly would Federer like to prevent that?
"It's not the driving force behind this match," Federer said. "It's to get to the next step, the final. That was my motivation when I entered the French Open. I'm looking forward to that match, because we always play fantastic."
For the better part of this fortnight, Federer has been talking about Djokovic almost as much as himself. Now, he could end all those questions about The Streak.
"Look, Novak has played fantastic," Federer said. "But I think the No. 1 thing is more important to him right now than the streak."
Federer wasn't exactly stressed against Monfils, but Djokovic, the beneficiary of a walkover in his quarterfinal match against Fabio Fognini, will have enjoyed a four-day rest when he steps onto Chatrier on Friday.
More than anyone in modern men's tennis, Federer generates astonishing numbers. In some ways, his streak of 23 Grand Slam semifinal appearances is almost impressive as his record-breaking 16 majors. Even though he'll celebrate his 30th birthday in August, he is functioning at a level beyond the comprehension of most in the game. He's 2-for-2 in reaching major semifinals this year, and going back to his first Grand Slam singles victory, he's a robust 28-for-32.
Afterward, Monfils was asked who would win the marquee semifinal match.
"I have no idea," he said, eyes widening. "As usual -- and we forget this -- Roger is very much present. He's got a lot of ambitions still. But Novak is playing so well, it will be an incredible semifinal. I will be the first one to watch the match."
Federer, by the texture and tone of his answers, seems quite at peace at the moment. He's been in Djokovic's spot before, in 2004.
"There's less at stake for me than for him," Federer said. "Sure, I'd love again to be in a Grand Slam final. I'm playing really well. I'll give everything I have, and then we'll talk about it later."
Greg Garber is a senior writer for ESPN.com.