Gael Monfils rose to the occasion as he upset Roger Federer 6-1, 6-4, 6-3 to help France level the Davis Cup final with Switzerland 1-1 on Friday.
After Stanislas Wawrinka had given the Swiss a 1-0 lead by beating Jo-Wilfried Tsonga 6-1, 3-6, 6-3, 6-2, Monfils was at his best against the world number two who has struggled recently with back problems.
Federer missed training this week after being forced to withdraw from his ATP World Tour Final against Novak Djokovic in London on Sunday.
"Clearly I did feel that I had not hit and played and moved at all for five days, and Gael played well," Federer said.
"It's not like I couldn't play at all. Those who saw the match saw that it was a proper match and he was the better player at the end."
Monfils, who had never beaten Federer on clay in four previous encounters, won five games in a row as he whizzed through the first set.
Struggling with his serve, the Swiss was broken again in the third game of the second set and his French rival showed no sign of weakening, sending his opponent chasing balls left, right and centre.
It was not game over yet, though, as Federer beat Monfils in five sets in this year's US Open quarterfinals after dropping the first two.
But this time, roared on by a record 27,432 crowd that were kept quiet during Tsonga's match, Monfils maintained his grip to break for a 3-2 lead before finishing off the contest on Federer's serve with a stunning backhand winner down the line.
"It's hard to say whether he is injured because I'm not necessarily looking at him," said Monfils. "But if he is here it is because he thinks he will beat you."
Switzerland looked as if they were in the driving seat after Wawrinka's defeat of Tsonga who looked a pale shadow of his normally aggressive self against the world number four.
"I was confident. I showed him on the court that I was better than he was," said Wawrinka.
Tsonga agreed with his rival.
"Stan was good today. He played a good match. That's it. There is nothing to say really," he said.
The doubles will be played on Saturday, with the reverse singles on Sunday on the clay of the Pierre Mauroy stadium.
France, who last lifted the trophy in 2001, are looking to win the Davis Cup for the 10th time while Switzerland are seeking their maiden title.
