Roger Federer was given a huge scare by Gilles Simon before fighting back to reach the quarter-finals.
The Swiss was looking to reach the last eight at a 36th consecutive grand slam, a record dating back to Wimbledon in 2004, 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.
There was no indication of the drama to come when Federer, who was bidding for his 900th tour-level victory, won six straight games to win the first set.
Tumble
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.
There is almost nowhere where Federer is more loved than Roland Garros, yet the crowd were overwhelming cheering for Simon.
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 helping his opponent out with quite a lot of errors but Simon, who needed five sets to defeat Lleyton Hewitt and Sam Querrey, was showing what a talented player he is.
In trouble
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 had returned to his side now as well, perhaps having thought twice about wanting to lose their favourite so early, 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 and he wrapped up victory in two hours and 59 minutes when Simon put a backhand wide.
