Monte Carlo, Monaco ? Roger Federer’s 25-match winning streak — the longest in men’s tennis since 1984 — ended Friday at the hands of a French teenager not even ranked in the top 100.

Richard Gasquet, an 18-year-old qualifier playing in just his fourth match of the year on the ATP Tour, jolted the world’s No. 1 player by saving three match points in a 6-7 (1), 6-2, 7-6 (8) victory to reach the Monte Carlo Masters semifinals.

“It feels surreal,” Gasquet said.

Federer, a four-time Grand Slam winner, was going for his third straight Masters Series title in this important clay-court event leading to the French Open.

“He’s definitely got all the tools,” the Swiss standout said. “It’s a matter of consistency. That’s what I was struggling with in the beginning. I think that’s what he was doing, too.”

Gasquet, ranked 101st, will face Spain’s Rafael Nadal, another 18-year-old, in today’s semifinals. Nadal, seeded 11th, defeated fourth-seeded Gaston Gaudio of Argentina, the French Open champion, 6-3, 6-0.

Juan Carlos Ferrero of Spain and defending champion Guillermo Coria of Argentina also won to reach the semis.

Richard Gasquet of France celebrates after winning a set against Roger Federer. Gasquet won, 6-7 (1), 6-2, 7-6 (8), Friday in Monte Carlo, Monaco.

Federer entered the match with a 35-1 record this year, the best ATP start since John McEnroe was 39-0 in 1984. His only previous loss was to Marat Safin in the Australian Open semis. Federer hadn’t lost in his last 35 matches against players outside the top 100.

“Of course, it’s frustrating,” Federer said. “He gave me a chance to come back in the match, which I should have taken. But he deserved to win.”

Ferrero, a two-time champion, advanced with a 6-2, 6-3 victory over Italy’s Filippo Volandri. Coria, seeded sixth, overcame a sloppy start to beat Spain’s David Ferrer, 3-6, 6-4, 6-3. Ferrero and Coria will meet in the semis in a rematch of the 2003 Monte Carlo final won by Ferrero.