Now comes the showdown everyone's been anticipating since the field was set nearly two weeks ago: A Djokovic vs. Nadal semifinal Friday that will have the feel of a final, and not only because they met for the championship at Roland Garros a year ago.
"A lot of people in the tennis world are looking to the matchup coming up with Rafa and Novak," said Haas, who at 35 was the oldest French Open quarterfinalist since 1971. "I'll definitely be watching."
Djokovic, ranked and seeded No. 1, against Nadal, owner of a record seven French Open titles, including three in a row.
Djokovic, trying to become the eighth man to complete a career Grand Slam, against Nadal, trying to become the only man to win eight trophies at one major tournament.
Djokovic owns six major titles, Nadal 11.
"I would prefer an easier opponent," Nadal said.
Djokovic is 33-4 this season and reached his 12th consecutive major semifinal, the second-longest streak in history.
Nadal is 41-2 since returning in February after missing seven months because of a left knee injury he declined to discuss Wednesday.
That absence is why Nadal's ranking slid and he was seeded No. 3, so was drawn to play Djokovic in the semifinals; their previous 11 matchups came in tournament finals.
"He never gives up. I mean, that's an impressive virtue that he has. Over the years, he's been so consistent and so dominant, on this surface especially," Djokovic said. "He's struggled with injuries, came back, and lost only a few matches since he came back. You've got to respect that."
It's all enough to render Friday's other semifinal something of an afterthought, even if local fans have a rooting interest when No. 6 Jo-Wilfried Tsonga of France faces No. 4 David Ferrer of Spain. Tsonga, who beat Roger Federer in the quarterfinals, wants to give France its first male champion at Roland Garros since Yannick Noah 30 years ago.
The women's semifinals Thursday are No. 1 Serena Williams against No. 5 Sara Errani, and No. 2 Maria Sharapova against No. 4 Victoria Azarenka. Sharapova, the defending champion, and Azarenka advanced Wednesday; Williams and Errani won their quarterfinals Tuesday.
While Ferrer and Tsonga have only met three times, Djokovic and Nadal will be playing each other for the 35th time the 10th at a Grand Slam tournament, the fifth at Roland Garros.
"We know each other's game really well," Djokovic said.
Nadal holds the edge in every category: 19-15 overall, 6-3 at majors, 4-0 in Paris, part of his 57-1 mark at the clay-court tournament.
But Djokovic did win their most recent encounter, in the final at Monte Carlo on clay in April.
"That is something that can maybe give me that mental edge when I step onto the court knowing I already won against him on clay this season. Knowing I can do it, even though not many players in last 10 years have won against him on this surface and he's been the most dominant player in the history of this sport on this surface," Djokovic said. "It's incredible what he does on this surface."
Just ask Wawrinka.
With the sun out, for a change, and the temperature up to 75 degrees (24 C), Nadal turned in his finest performance of these two weeks, displaying his particular brand of relentless ball-chasing on on-target shotmaking, with only 17 unforced errors less than one per game.
"Today, I think, his level was really high," said Toni Nadal, Rafael's uncle and coach.
Wawrinka's coach, Magnus Norman, was working with Robin Soderling back in 2009, when Soderling stunned Nadal in the French Open's fourth round. That remains Nadal's only loss in nine appearances in the tournament.
Norman couldn't help Wawrinka pull off the same sort of surprise against Nadal.
"He was too strong," Norman said.
After dropping the first set in each of the first two rounds, Nadal has won 12 sets in a row, looking better each time out.
"Obviously I really am playing better here. I'm happy the way that I played today, especially. Was my best match of the tournament, without any doubt," Nadal said. "I was not happy five days ago."
For the first time since 1948, all four men's quarterfinals at the French Open were decided in straight sets, and that sort of result isn't very surprising when Nadal faces Wawrinka. Nadal has won all 10 matches, and all 22 sets, they've played.
Coming off a five-set victory in the fourth round, Wawrinka insisted fatigue was hardly the real issue Wednesday.
"I was not exhausted," Wawrinka explained, "but I was fighting against Nadal."
Djokovic's turn next.
Against Haas, Djokovic won 40 of the first 43 points he served, and the only moment of real tension came at 5-all in the second-set tiebreaker.
But Djokovic hit a backhand winner to close a 24-stroke exchange, the longest of the match, then won that set when Haas sent a backhand wide.
"When you don't win the big points against these type of guys," Haas said, "it gets very, very tough."
Djokovic has said repeatedly that his top priority this year is adding a French Open championship to his four from the Australian Open and one each from Wimbledon and the U.S. Open.
He's also determined to lift the trophy Sunday in honor of his childhood coach, who passed away last weekend.
"He is playing terrific tennis," Haas said. "He's got a quest, obviously, to win this title."
To do that, Djokovic must first get past Nadal.
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O Rafael Nadal wins 6-2, 6-3, 6-1 and Novak Djokovic wins 6-3, 7-6 (5), 7-5 on Wednesday to set up a semifinal match between the two.
O Women's semifinals
Thursday, 3 a.m.
TV • ESPN2