Nadal was well below his best as Mahut set up an all-French semi-final against Arnaud Clement with an impressive 7-5, 7-6 (7/0) victory over the top seed.

The Spaniard had arrived at the Wimbledon warm-up event on the back of another triumphant clay-court campaign that had concluded with his third consecutive Roland Garros title last Sunday.

But he remains less than comfortable on grass and Mahut took advantage as he savoured the best day of his career. Nadal had quickly wrapped up the one game he needed to beat Max Mirnyi 7-6 (7/3), 6-3 in his rain-delayed third round match earlier on Friday.

But the world number two still looked lethargic against an opponent who had already played virtually a full match on Friday afternoon.

Mahut, ranked 106th in the world, had beaten fifth seed Ivan Ljubicic 7-6 (7/3), 6-3 to reach his first quarterfinal of the season and was back on court just hours later.

The 25-year-old showed no signs of flagging and gave Nadal his most rigorous test for weeks. He refused to be bullied by Nadal's power-play and took the first set after breaking in the 12th game.

Nadal had chances to move in front in the second set but squandered four break points in the 11th game.

Mahut showed no sign of nerves as the set went to a tie-break and Nadal gifted him a memorable scalp with a series of unforced errors as he lost the breaker to love.

Nadal said: "It was tough. I really didn't play very well. I tried my best with the best attitude, but I only had one or two chances.

"He served very well but I'm happy with my tournament. It is difficult to play every day and to get to the quarter-final on grass is not so bad for me."

Andy Roddick remained on course for a fourth Queen's title after easing into the semifinals with a 6-4, 7-6 (7/5) victory over Croatian wild card Marin Cilic.

Roddick, the second seed, had too much grasscourt experience for his teenage opponent and now faces Dmitry Tursunov.

The American won the Wimbledon warm-up event on three successive occasions from 2002 to 2005 and will believe he can tie the record of four singles crowns held by Lleyton Hewitt, Boris Becker and John McEnroe.

Despite his victory Roddick insisted he can still improve.

"If I want to win the tournament I will have to do better than that. I played two good games and then a sloppy one. I wasn't moving as well as I wanted and everything just needs to be a bit sharper," said the world number three.

Cilic, ranked 110th in the world, was understandably nervous in the early stages and struggled to find his range on serve. Roddick took advantage, breaking the teenager in the first game and cruising to a one-set lead.

Roddick was a break down in the second set but he was able to slug his way back into the match as a succession of brutal forehands clinched a break in the seventh game.

The tie-break appeared to be going Cilic's way as he raced into a 5-2 lead, but, although Roddick was never at his best, he kept his nerve and clawed back the deficit before a wild return from Cilic handed him the match.

Fernando Gonzalez suffered a spectacular meltdown as the Chilean third seed crashed out against Tursunov.

Gonzalez was cruising towards the semi-finals when he led 4-2 in the final set, but he suddenly lost his cool, allowing Tursunov to break back before destroying his racket and then losing the final three games to go out 3-6, 7-6 (7/5), 4-6.

Tursunov, the seventh seed, was relieved to have overcome the frequent rain breaks to beat this year's Australian Open runner-up.

"The rain delays are difficult," Tursunov said. "It's something about being in Britain! I just tried to keep my patience during the breaks and not coming out playing too many shots."

Clement, the 14th seed, ended the day tired but elated after reaching the last four with back to back to back wins over Novak Djokovic and then Ivo Karlovic.

Frenchman Clement shocked fourth seed Djokovic, winning 2-6, 6-3, 6-4 in his rain-delayed third round match. He then came back on court later Friday to secure a 7-5, 6-4 victory over Croatian Ivo Karlovic.