Clay king Rafael Nadal motored back into his French Open comfort zone with a commanding 7-6 (7-2), 7-6 (7-3), 6-4 defeat of fellow Spaniard Nicolas Almagro to reach a Paris semi-final for the fifth time in six years.
The Spaniard will have a surprise opponent after Austrian Jurgen Melzer played the match of his life, coming from two sets to love down to upset third seed Novak Djokovic 3-6, 2-6, 6-2, 7-6 (7-3), 6-4.
The struggle lasted for four and a quarter hours, with the 29-year-old winner able to convert on only four of 24 break chances against the two-time semi-finalist.
The Serb saved two match points in the dramatic final game, the first as a nervous Melzer missed an easy volley at the net and the second from a Djokovic winner.
But a service return long from the seed finally gave Melzer the biggest win of his career.
"This is a great moment, historic for my career," said the overjoyed winner, who came from two sets to love down for the first time in his career. "It was so tough."
"A lot of thing went through my head during the match. When I was down two sets, I was still playing well. I stuck to my game plan, this is fantastic."
Nadal owns a 2-0 record over Melzer, with their last meeting on Madrid clay a year ago.
Second seed Nadal, who could take back the number one ranking, should he claim a fifth title on Sunday, thanks to the loss by holder Roger Federer against Robin Soderling, notched his seventh victory without a loss against compatriot Almagro, with five of the wins coming on clay.
Despite a rock-steady performance, Nadal refuses to list himself as a title favourite. "I'm sorry for Roger losing, but for me right now there is not a favourite," said the six-time Grand Slam champion.
Nadal now stands 36-1 at Roland Garros after his lone loss a year ago to Soderling. His win over Almagro came three weeks after a similar one in Madrid, a comeback from a set down.
"This was not an easy match, he's a good player," said Nadal. "It's always an unbelievable dream to be in the semi-finals here, especially after losing last year.
In the women's draw, Samantha Stosur outlasted frustrated top seed Serena Williams 6-2, 6-7 (2-7), 8-6 to reach her second straight Paris semi-final.
World number one Williams was left adrift by the efficient forehands of the no-nonsense Australian as Stosur duplicated her breakthrough semi-final of a year ago.
The Australian completed the Paris elimination of the Williams sisters as she followed-up on her fourth-round upset of four-time winner Justine Henin. Venus Williams was beaten by Russia's Nadia Petrova in the fourth round.
Stosur, whose record on clay this spring is an outstanding 18-2, will next face off against Serbian fourth seed Jelena Jankovic, a winner over Yaraslava Shvedova of Kazakhstan 7-5, 6-4.