Roger Federer was given a huge scare by Gilles Simon before fighting back to reach the French Open quarter-finals.
The Swiss was looking to reach the last eight at a 36th consecutive grand slam, and only five times before in that run had he been behind going into the fourth set.
In the end, Federer did what he has done on those other five occasions, recovering to win 6-1 4-6 2-6 6-2 6-3, but there was plenty to give hope to his next opponent, sixth seed Jo-Wilfried Tsonga.
Federer, who was bidding for his 900th tour-level victory, won six straight games to win the first set, looking in fine fettle and even hitting a winner around the net post.
The pair met in Rome two weeks ago, when Simon won only three games, but the Frenchman had given Federer trouble in the past. The match turned in the middle of the second set. Federer took a tumble and, although he was not hurt, it seemed to upset the rhythm of the second seed.
Simon broke immediately to lead 4-3 and then levelled the match on his first set point when Federer fired a backhand long.
And it was to get even better for the 28-year-old, who broke again for 3-2 in the third set before winning the set with his fifth game in a row.
Federer was in trouble, but the 31-year-old has dug himself out of deeper holes in the past and set about turning things back in his favour.
The crowd were now behind him and Federer clenched his fist as he broke for 4-2 in the fourth.
The 2009 champion looked in complete control as he reeled off seven straight games before Simon dug in with an admirable hold for 1-3 in the decider. It was not quite over, and the Frenchman had two chances to retrieve the break with Federer serving for the match, but his serve saved the Swiss .
Jonny Marray and Heather Watson, meanwhile, were beaten in the mixed doubles by the French pairing of Alize Lim and Jeremy Chardy on Saturday.