Novak Djokovic and Roger Federer survived five-set struggles at the French Open on Tuesday to set up a mouth-watering semi-final where the Swiss legend will attempt to shatter the world number one's Grand Slam dream.
Top seed Djokovic saved four match points against Jo-Wilfried Tsonga before pulling off a nail-biting 6-1, 5-7, 5-7, 7-6 (8/6), 6-1 quarter-final win.
Third seed Federer reached a record-equalling 31st Grand Slam semi-final when he survived a brutal barrage from frail Argentine Juan Martin del Potro before prevailing 3-6, 6-7 (4/7), 6-2, 6-0, 6-3.
After his triumphs at Wimbledon, the US Open and the Australian Open, Serb star Djokovic is bidding to become just the third man to hold all four Grand Slam titles at the same time and the first in 43 years.
His win over Tsonga made it 26 straight match victories in Grand Slams, but seldom has he been run so ragged as he was at times by the powerful Frenchman, who had let slip four match points in the fourth set.
The defeat meant Tsonga's dream of becoming the first Frenchman to win at Roland Garros since Yannick Noah in 1983 had been cruelly shattered.
"He was the better player for most of the match and I was fortunate to come back from four match points down. It was an incredible match," said Djokovic, who had needed five sets to beat Italy's Andreas Seppi in the fourth round.
Heartbroken Tsonga said: "I did what I said I would and gave everything. I came close and I would have loved to have won. It's a shame because I was pretty close, but at the end I had no energy left. Now I will have to close this chapter."
The key part of the tie was in the ninth game of the fourth set when Tsonga had two match points only for Djokovic to hold firm. Two games later two more match points escaped the Frenchman setting up a tie-break.
Djokovic trailed 2-4 in that, but with Tsonga looking increasingly tight, the top seed clawed his way back and forced a fifth set on his third set point
The world number one seized the occasion to jump out into a 3-0 lead and he raced away to pull off a stunning victory.
Federer, the 16-time Grand Slam title winner and 2009 champion in Paris, came back from two sets to love down for the seventh time in his career and will take on Djokovic for the 26th time with a place in Sunday's final at stake.
The result was cruel luck on the 1.98m Del Potro who had looked on course for a straight sets win after unleashing a brutal wave of power-hitting off both wings which left Federer floundering in the first two sets.
However, his hopes were finally sabotaged by a recurrence of the knee injury which has plagued him in Paris and which left him struggling to move by the end of Tuesday's match.
"I knew Juan Martin's knee was bothering him and was trying to finish the rallies quickly," said Federer, who has pulled level with Jimmy Connors' mark of 31 Grand Slam semi-finals.
"I knew it would be a big fight today. I played well tactically and was strong mentally because there wasn't a lot in it."
Federer, playing in his 50th straight Grand Slam tournament and 32nd consecutive quarter-final at the majors, took an 11-2 career advantage over the towering Argentine into Tuesday's clash.
One of those wins came in a gripping Roland Garros semi-final in 2009 when he twice fought back from a set deficit to win in five before Del Potro gained revenge three months later with a first Grand Slam title triumph at the US Open.
The 23-year-old Argentine had lost all five meetings with the Swiss since returning after almost a year out from wrist surgery in 2011.
"I played a great match, but in the third and fourth sets, he started to play a lot better than he did at the beginning," said Del Potro, who insisted his knee was not a problem.
"I called the trainer to have the tape loosened on my knee, but there was no problem. I just served really badly in the fourth set and you won't get many points against the top guys if you do that. He took his opportunities and won."
The two remaining quarter-finals will take place on Wednesday when six-time champion Rafael Nadal meets fellow Spaniard Nicolas Almagro boasting a 7-0 career advantage.
Fourth seeded Andy Murray faces Spain's David Ferrer, defending a 5-4 series lead.
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