Paris - Roger Federer was knocked out of the French Open at the quarter-final stage on Tuesday, falling in three sets to fellow Swiss Stan Wawrinka, the eighth seed, 6-4, 6-3, 7-6 (7/4).
Federer, the second seed and 2009 champion at Roland Garros, had only ever lost twice in 18 previous meetings with his compatriot but was well beaten on a windy Court Suzanne Lenglen.
The 17-time Grand Slam champion proved incapable of breaking his opponent's serve at all over the course of a match that lasted two hours and nine minutes.
Remarkably, it was just the third time in his career he had failed to break an opponent's serve in a Grand Slam match -- the last came against Max Mirnyi at the US Open in 2002 when he was aged just 21 and had not yet won a major.
It is a further sign of the decline of the 33-year-old, who was also beaten in the third round of the Australian Open earlier this year by Italy's Andreas Seppi.
Federer's last Grand Slam title was almost three years ago when he captured his seventh Wimbledon title in 2012.
In contrast, Wawrinka broke decisively in the first set and then twice more in the second. There were no breaks in a far tighter third set, but Wawrinka won it on his second match point in the tiebreak.
"We know Stan can do this and it's nice for him and important for him to string it together and do well. I thought he played really great tennis today," said a diplomatic Federer, who admitted his opponent handled the blustery conditions far better.
"It was tough so it's all the more impressive the way Stan was able to play."
Through to his first ever French Open semi-final, Wawrinka will face the winner of Tuesday's other quarter-final between Japan's fifth seed Kei Nishikori and home hope Jo-Wilfried Tsonga, the 14th seed.
"Today was my best match on clay and it's an incredible moment for me. The conditions were difficult with a lot of wind but I believed in my game and it was a really incredible match from me," said Wawrinka, who was the junior champion at Roland Garros in 2003.
The 2014 Australian Open champion's run in Paris comes after he beat Rafael Nadal at the Rome Masters recently before losing to Federer in the semi-finals.
"I'm playing good tennis and I'm really pleased to be in Paris semi-finals for first time," he added after defeating his more illustrious compatriot at a Grand Slam for the first time.
Elsewhere on Tuesday, the quarter-final between Nishikori and Tsonga on the main Court Philippe Chatrier was held up for more than half an hour when a metal sheet from a giant video screen was blown off in high winds, crashing into spectators and leaving three with minor injuries.
Spectators were briefly ushered out of the affected section of the 14,911-seat arena before eventually being allowed to return as action got underway on a day when Roland Garros was hit by gusts of more than 50 km/h.
The standout quarter-final on Wednesday will see reigning champion Rafael Nadal, seeded six, put his dominance of the clay-court Grand Slam on the line against world number one Novak Djokovic, who has won his last 26 matches.
The winner of that will take on the winner of the other last-eight match between third seed Andy Murray and seventh seed David Ferrer, the runner-up in 2013.
Results from the 10th day of the French Open at Roland Garros on Tuesday (x denotes seeded player):
Jo-Wilfried Tsonga (FRA x14) bt Kei Nishikori (JPN x5) 6-1, 6-4, 4-6, 3-6, 6-3
Stan Wawrinka (SUI x8) bt Roger Federer (SUI x2) 6-4, 6-3, 7-6 (7/4)
Ana Ivanovic (SRB x7) bt Elina Svitolina (UKR x19) 6-3, 6-2
Lucie Safarova (CZE x13) bt Garbiñe Muguruza (ESP x21) 7-6 (7/3), 6-3