Monte Carlo - Eight-time champion Rafael Nadal slumped to a shock Monte Carlo Masters quarter-final defeat to compatriot and close friend David Ferrer on Friday while Roger Federer scraped into the last-four.
Ferrer claimed a famous 7-6 (7/1), 6-4 win to hand the top seed only his third loss in the principality just a day after Nadal had won his 300th career claycourt match and 50th at the Monte Carlo Country Club.
Meanwhile Federer, bidding to win the title for the first time, squandered his first 15 break points before finally coming good on a 16th on his way to a 2-6, 7-6 (8/6), 6-1 defeat of French ninth seed Jo-Wilfried Tsonga.
The Swiss fourth seed won his 950th career match in a topsy-turvy clash, winning the second set on a fourth set point before running away with the third.
He will be playing in his 50th Masters semi-final against either defending champion Novak Djokovic or Spain's Guillermo Garcia-Lopez, the title winner on clay in Casablanca last weekend.
Ferrer came to the court on Friday with a 5-21 deficit against Nadal who last failed to make the final in Monte Carlo in his debut year of 2003.
"When the opponent is doing things better than you, the normal thing is to lose. That's what happened today," said Nadal, who committed 44 unforced errors.
"I didn't play the right way. I didn't play with the right intensity with my forehand. I played too short. I give him the chance to have the control of the point almost all the time. He did much better than me, so I just congratulate him."
Ferrer will now face off on Saturday against Australian Open winner Stanislas Wawrinka who clinched a 7-6 (7/5), 6-2 over Canadian Milos Raonic.
Nadal's only other losses at the tournament occurred in the 2003 third round against Guillermo Coria and last year when he went down in straight sets to Djokovic in the final.
Prior to that final, he had won eight straight editions.
"I'm not happy today about what I did, not very happy about the way that I played the second set after losing the first," continued Nadal.
"I didn't play with the right intensity at the beginning of the second. I gave him a big opportunity at the beginning of the second."
Nadal was well off the boil from the start in a contest where the opening set took 75 minutes and the third game required a quarter of an hour.
Ferrer battled his nerves as he served for victory leading 5-2, but was broken. On his second chance, the 32-year-old got the job done after two hours, 11 minutes.
The win was the first on clay for Ferrer against Nadal in a decade.
"The last time I beat Rafael on clay was 10 years ago. But I'm happy because I am in the semi-final and because I am playing very good this week," said Ferrer, who was runner-up to Nadal at the French Open last year.
"Maybe this week is my best of this season. Rafa's not a machine. Sometimes he can play not so good. Maybe today he didn't play his best tennis, and I played very good."
Wawrinka, who had a walkover in the previous round when Spain's Nicolas Almagro pulled out with a foot injury, took control of his match as Raonic twice lost leads in the opening set tie-breaker.
The mistakes gave an opening to Wawrinka, who took the first set on his initial opportunity and then broke to start the second as the frustrated Raonic let go of a 40-15 lead in the first game.
From that point on, momentum totally shifted to the Swiss world number three, who broke the Canadian again for 5-2 before serving out for the match in 90 minutes.
"I showed him on every point that the match will be tough for him," said the winner. "Even in the first set he was staying with me. He was close to winning the tie-break.
"But it was a tough set for him because he had to play his best, he had to always try something.
"I felt strong from the baseline, I feel good physically. I know that on clay courts if I play my best tennis I can beat those guys."
Wawrinka duplicated his 2009 result by reaching the semi-finals and improving his season record to 18-3.
Stanislas Wawrinka (SUI x3) bt Milos Raonic (CAN x8) 7-6 (7/5), 6-2
David Ferrer (ESP x6) bt Rafael Nadal (ESP x1) 7-6 (7/1), 6-4
Roger Federer (SUI x4) bt Jo-Wilfried Tsonga (FRA x9) 2-6, 7-6 (8/6), 6-1