(CNN) - After winning his quarterfinal at the French Open, Roger Federer addressed the crowd, not to mention plenty more watching on TV around the world.
"Maybe the reason I came back to play on clay was to play Rafa," Federer said.
If that is true, Federer got his wish after he downed fellow Swiss Stan Wawrinka 7-6 (4) 4-6 7-6 (5) 6-4 in a bruising three-and-a-half hour duel on court Suzanne Lenglen.
Next up is his old foe, the 11-time champion Rafael Nadal, who dispatched Kei Nishikori 6-1 6-1 6-3 in under two hours on the main Philippe Chatrier court.
Such was the difference in duration in the matches that they finished at around the same time -- after a rain delay of more than an hour in soggy and windy Paris -- despite Federer opening the day's play on his court and Nadal playing second on Philippe Chatrier.
The last time veterans Federer and Nadal tangled on clay came in Rome in 2013. And at the French Open it was in the 2011 final. Nadal leads 13-2 on dirt and 5-0 in Paris.
They are first and second among the men in grand slam victories, Federer on 20 and Nadal on 17. Federer, though, is back on clay this season after a gap of more than two years.
"Having Roger in front, in the semifinals, is an extra thing," said Nadal, who celebrated his 33rd birthday Monday. "We shared the most important moments of our careers together on court facing each other.
"So it's another episode of this, and happy for that and excited, no? Will be a special moment, and let's try to be ready for it."
The chances of them ever meeting again on the clay appeared over after Federer appeared to have retired from the clay-court swing ahead of Roland Garros in 2016, preferring to preserve his body and focus on Wimbledon, where he has won a record eight titles.
But the 37-year-old decided to return to Paris for the first time since 2015 this year, and when he contests his first French Open semifinal since 2012, shouldn't be discounted.
In the first match on center court, Johanna Konta put in a flawless performance to beat 2018 finalist Sloane Stephens 6-1 6-4 to become the first British woman to make the last four in Paris since Jo Durie in 1983. She will meet Marketa Vondrousova, one of the two teenagers remaining in the draw.
The Swiss has won his last five matches against the left-handed spin master, and perhaps not facing Nadal on clay for a while has diminished the scars from past defeats, including in the 2008 final at Roland Garros when Federer claimed just four games.
A month later, Nadal added salt to the wounds when he beat Federer in his backyard of Wimbledon in what many consider the greatest tennis match of all time.
Given he sat in the half of the draw that started first, Federer also has an extra day to recover for the blockbuster. He insists he is looking forward to Friday.
"I'm very happy to play Rafa, because if you want to do or achieve something on the clay, inevitably, at some stage, you will go through Rafa, because he's that strong and he will be there," said Federer.
"I knew that when I signed up for the clay that hopefully that's gonna happen. If I would have had a different mindset to avoid him, then I should not have played the clay. So I think by that mindset, I think it helped me to play so well so far this tournament."
Federer has said beating Nadal in the 2017 Australian Open final was one of the biggest highlights of a career filled with trophies -- it had been a decade since he triumphed over the Spaniard at a major.
A victory over Nadal at the French Open for the first time and at his very advanced tennis age would have to rank up there, too.
Yet for a while Tuesday, it looked Federer would never get there.
Tied in sets with Wawrinka, seeing break point after break point evaporate and squandering two set points at 5-4 in the third, Federer then faced two break points in the ensuing game.
On the first, Wawrinka struck a fine drop shot from the service line with Federer in a troublesome position. Instead of moving in, Wawrinka lost his advantage in court positioning and moved back.
Federer pushed his forehand down the line and Wawrinka's backhand -- he slipped striking his favorite stroke -- went into the net.
Just as he did in the first set tiebreak, Federer raced out to an early lead and held on.
Helping Federer get through the third set was serving and volleying repeatedly on second serves as Wawrinka returned from around the backboard.
Federer found himself at the net often and impressed, winning 41 of 60 points.
He survived two double faults and a break point in the last game to close out the 2015 champion, who left to great applause.
Federer improved to 23-3 against his pal, not paying the price for going only 2-for-18 on break points four months after he went 0-for-12 in a fourth-round Australian Open loss to Stefanos Tsitsipas.
Despite the defeat, it was a gutsy display from Wawrinka after his five-hour classic with Tsitsipas on Sunday. He showed he is back after knee surgery in 2017.
Nishikori also endured a marathon against Benoit Paire that concluded Monday. This after a five-set win over Laslo Djere.
Tough for Nishikori
The Japanese, the 2014 US Open finalist, plays more five sets early in majors than he would like and the result is little left in the tank for the business end against some of the best ever.
He was forced to retire against current No. 1 Novak Djokovic in the Australian Open quarterfinals and couldn't offer up much against Nadal, either.
Federer, Nadal, Djokovic -- who faces Alexander Zverev on Wednesday -- and Andy Murray comprise the big four in men's tennis.
Murray isn't on tour as he prepares to return from longstanding hip issues at a tournament in London in doubles in June but his fellow Brit Konta is. The 26th seed is in the midst of a career revival.
The precedents are there -- Jelena Ostapenko had never won a match at the French Open, then claimed the title in 2017.
Will the big-serving Konta, a semifinalist at Wimbledon two years ago, duplicate that feat in 2019? She had been 0-4 entering this edition.
For a spot in the final, she will meet left-hander Vondrousova, another player who enjoyed a fruitful French Open buildup.
The 38th-ranked Vondrousova defeated 31st seed Petra Martic 7-6 (1) 7-5, two months after the Croatian topped her in a final in Istanbul.
In another thriller on Lenglen filled with dazzling variety, Martic crucially couldn't serve out the first at 5-3 and missed three straight set points at 6-5.
Federer and Nadal will play on Chatrier and Wawrinka, for one, will be tuning despite his defeat.
"'I'm a big fan of this sport. So when you get the chance to have in the semifinal of the French Open Roger against Rafa, you're gonna put the TV on and watch," he said.
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