Benneteau burst into tears after his spectacular victory
Julien Benneteau caused a huge upset at the Paris Masters as he beat top seed Roger Federer 3-6 7-6 (7-4) 6-4.
The world number one began in his usual imperious form but his game began to unravel as errors crept in.
Backed by an enthusiastic home crowd, Benneteau seized on his opponent's weakness, set up match point with a superb backhand and won it with an ace.
Earlier, Rafael Nadal had to save five match points to beat fellow Spaniard Nicolas Almagro 3-6 7-6 (7-2) 7-5.
"He played incredible at the end. Julien went out and got the victory," Federer said after his shock defeat.
"I definitely had chances. I missed them. I feel fine physically, and mentally I was fresh to do really well here.
"I didn't have my rhythm from the baseline. Every time I had a chance he was winning the point."
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An overwhelmed Beneteau said: "It's magic. It's fabulous. Everything you can imagine. The memories will stay with me forever.
"Hearing the crowd when they are all behind you, the noise is enormous. I didn't believe it was possible to experience something like this."
Almagro took the first set against Nadal 6-3 and had five chances to win it in the second, but the Spaniard showed tremendous mental strength to stay in the match.
He won the tie-break 7-2 before Almagro succumbed to cramp in the third to allow Nadal to win the decider 7-5.
Nadal, who has never won the Paris Masters and who has not won a tournament since May, looked decidedly rusty in the first set, which Almagro took comfortably.
The unseeded Almagro, who had never won a set against Nadal in four previous meetings, saved a set point at 4-5 in the second before breaking Nadal in the next game.
I am very lucky to be in the next round. That's the truth. I played bad but I won, which is the one positive thing
But after going 40-0 down, Nadal produced some brilliant winners to save five match points and break back, before running away with the tie-break.
The pair traded breaks in the third set, and Almagro served for the match at 5-3 but was broken.
Almagro, who had required treatment for cramp at 3-3, could barely move from that point on and Nadal managed to get the telling break in the 11th game.
"I played great tennis in only one moment, but in the rest of the match I didn't play well," admitted Nadal aftewards.
"I am very lucky to be in the next round. That's the truth. I played bad but I won, which is the one positive thing."
His next opponent is another Spaniard,
Tommy Robredo, who saw off Tomas Berdych of the Czech Republic 6-4 6-4.
Novak Djokovic of Serbia advanced to the third round by beating Juan Monaco of Argentina 6-3 7-5.
And ninth seed
Robin Soderling of Sweden beat Ivo Karlovic of Croatia 6-4 7-6 (7-6) to keep alive his slim hopes of qualifying for the eight-man ATP World Tour Finals later this month.
US Open champion and fifth seed
Juan Martin del Potro beat Russia's Marat Safin, playing in his last tournament, 6-4 5-7 6-4.
Arnaud Clement of France defeated 16th seed Tommy Haas of Germany 5-7 6-3 7-6 (8-6), and 10th seed Fernando Gonzalez of Chile beat American John Isner 7-5 7-6 (7-3).