Andy Murray produced a late surge to beat Gael Monfils in five sets and reach the French Open semi-finals.
The Briton let a two-set lead slip but raced through the fifth to win 6-4 6-1 4-6 1-6 6-0 in near darkness at 21:40 local time.
Murray goes on to face eight-time champion Rafael Nadal in a repeat of the 2011 semi-final.
Nadal fought back to beat fellow Spaniard and fifth seed David Ferrer 4-6 6-4 6-0 6-1.
"It was a hard match," said Murray. "Conditions changed quite a lot during it.
"It was extremely windy in the beginning and then it was pretty calm at the end and very slow."
Murray, who said it got very cold towards the end of the contest, praise Monfils for his resilience.
"He really raised his game in the third set," said the Scot. "I thought I played a pretty good third set. The fourth set wasn't my best, but it was a fun match."
Murray, 27, had played superbly to move two sets clear on Court Philippe Chatrier, driving Monfils to distraction - and quietening the crowd - with his variety of pace and spin.
When he had break points early in the third against Monfils, a straight-sets win looked almost inevitable, but the Frenchman clung on.
Serving first in the set, Monfils's opportunity arrived at 5-4 when Murray floated a backhand long to fall to 15-40, and when the Briton went long again two points later, the Frenchman and his supporters roared as one.
Murray had battled through cramp when taken to five sets over two days in the third round against Philipp Kohlschreiber, and he appeared to be struggling physically again.
Monfils, 27, stormed through the fourth set in 30 minutes and it began to look as though only the gathering darkness could stop the 23rd seed.
Referee Stefan Fransson came onto court to assess the light and insisted they play on into a fifth set, with Monfils clearly keen to continue.
"I didn't want to stop the match either," said Murray. "I was told we had 20 minutes left, so, you could potentially play two games, two or three games in that time.
"Six was the maximum that you could play. I mean, it was so dark at the end."
The Wimbledon champion was wobbling badly at 15-30 in the opening game, but Monfils missed an inviting backhand and suddenly the momentum was at the other end of the court.
A newly energised Murray rediscovered his attacking intent and leapt on a volley to break for 2-0, punching his fist in celebration, and then hit a spectacular running forehand for 3-0.
Monfils had no more to give and the errors began to flow, gifting Murray a second break, and it was the Frenchman who was now concerned about the light as his hopes of victory disappeared.
Murray clambered all over the Monfils serve one last time to earn three match points in game six, and he swatted away the second to seal a remarkable victory after three hours and 15 minutes.
"It was getting a bit dark, we couldn't see all that well, but I really wanted to finish because I knew that he was not in great shape," said Monfils.
"Maybe that's why I was a bit rushed in attacking him. I'm very frustrated."