The Swiss No 3 reaches his record-tying 31st grand slam semi-final after battling with Juan Martin Del Potro, and the Serb world No 1 survives his own marathon against Jo-Wilfried Tsonga.
Roger Federer and Novak Djokovic face five-set fights
What started as a replay of a US Open nightmare turned into something much better for Roger Federer: a trip to the French Open semi-finals.
Federer overcame a two-set deficit for the seventh time in his career on Tuesday to defeat Juan Martin del Potro 3-6, 6-7, 6-2, 6-0, 6-3.
It was Del Potro who famously beat Federer at the Flushing Meadows final in 2009 when the Swiss star was on top of the tennis world.
Yesterday's win means a record-tying 31st grand slam semi-final for the third-seeded Federer.
But for two sets it looked like the 16-time grand slam champion was on his way home, with Federer particularly out of sorts in the opener on a cool and damp Court Suzanne Lenglen.
But Del Potro has been struggling with a left knee injury and, after he edged a very tight second on a tiebreak, his movement became gradually worse.
"I knew Juan Martin's knee was bothering him and was trying to finish the rallies quickly," said Federer.
"I knew it would be a big fight today."
The Argentine's decline coincided with a marked improvement from Federer, and in the end the third seed came through the last three sets reasonably comfortably. The 30 year old had struggled to find his best form in all his previous four matches, dropping sets in three of them despite not facing anyone ranked higher than 78th.
In the first set he was particularly off colour, making a host of unforced errors, and Del Potro was able to play well within himself and still win it easily.
The second looked like being the key to the match.
Federer, who had beaten Del Potro five times in a row since losing to him in that US Open final, was battling himself, letting out a roar of frustration when he put another forehand over the baseline in the fifth game.
He still managed to break, though, this time a forehand proving too good for Del Potro, only to give it straight back with the tamest of forehands into the net.
Both pushed for the advantage - Del Potro had a chance in the eighth game but just missed with a forehand, then in the next game Federer brought up three chances but could not take any of them.
He thought he had with a forehand that was called good but it was overruled by umpire Pascal Maria.
The raw power of the Argentine was simply too much for Federer, with the ninth seed winning some brutal rallies despite the best efforts of the 2009 champion.
Federer had not fought back from two sets down to win since a first-round match at Wimbledon in 2010 against Alejandro Falla, but he made the best possible start to the third with an early break when Del Potro double faulted.
And it soon became clear the 23 year old, who has had heavy strapping on his left knee all tournament, was struggling.
The fourth set was a breeze for Federer, but he still had to save two break points at the start of the decider, both with tremendous forehands, as Del Potro steeled himself for one big effort.
The crucial break came in the fourth game, a curling forehand winner down the line leaving his opponent flat-footed, and he had little trouble holding on to his advantage, sealing victory on his second match point when Del Potro's forehand hit the top of the net and drifted wide.
Federer's 31st grand slam semi-final equals the record set by Jimmy Connors while he has also now reached at least the last four seven times or more at every slam.
"He was the better player for most of the match," Djokovic said of Tsonga.
"I was fortunate to come back from four match points down.
"It was an incredible match."
NO LIGHTS FOR ROLAND GARROS UNTIL 2017
Stanislas Wawrinka and the other players complaining that the French Open does not have lights on its courts are going to have to wait years for an upgrade.
Gilbert Ysern, the tournament director, says change is not coming until 2017, when a retractable roof and lights are slated to be installed at the main stadium at Roland Garros.
“It’s a topic that is a bit sensitive,” Ysern said. “We have a complex that has been approved for competition during the day, not at night. We are not allowed to play at night. That’s what the law says.”
After losing to Tsonga in the fourth round in a match that eventually ended on Monday after being suspended by darkness at 4-2 in the fifth set on Sunday evening, Wawrinka said that he thought the lack of lights at the French Open is “a big problem”.
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