Rafael Nadal was locked in a tight, compelling and lengthy French Open semifinal Friday when his opponent, third-seeded Alexander Zverev, ran to his right to chase a shot and twisted his right ankle. Zverev crumpled to the ground, wailing in agony and clutching at his lower leg.

His black outfit, arms and legs caked with rust-colored clay, Zverev was helped up by a trainer, then taken away from the court in a wheelchair. Minutes later, Zverev came back out onto Court Philippe Chatrier on crutches, his right shoe removed, and conceded the match, unable to continue.

The sudden end to a contest that was 3 hours old but not even through two full sets allowed Nadal to become, on his 36th birthday, the second-oldest men’s finalist in French Open history. Now he will try to become the oldest champion at a tournament he’s already won a record 13 times.

“Being in the final of Roland Garros is a dream, without a doubt,” Nadal said during an on-court interview, then revealed he had seen Zverev crying in a small room in the stadium.

“Very tough, no? And very sad for him, honestly, no?” Nadal told the full house of 15,000 spectators who had loudly tried to encourage him throughout the match, chanting “Ra-fa!” repeatedly.

With the pitter-patter of rain audible against the closed retractable roof at Court Philippe Chatier, Nadal emerged to claim a tight-as-can-be, draining first set that lasted 1 1/2 hours by a 7-6 (8) score. The second set also was headed to a tiebreaker after another 1 1/2 hours when Zverev tumbled behind the baseline.

A trainer came out to attend to him, and Nadal walked around the net to check on Zverev, too. After Zverev returned and said he would need to retire from the match, he shook the chair umpire’s hand and then hugged Nadal.

Nadal has been dealing with chronic pain in his left foot and was coming off a pair of victories that each lasted more than 4 hours — including against defending champion Novak Djokovic on Tuesday — but showed no signs of age, injury or fatigue against the 25-year-old Zverev.

In addition to bidding for a 14th trophy from the French Open, Nadal can claim his 22nd Grand Slam title to add to the men’s record he already holds after his triumph at the Australian Open in January.

Djokovic and Roger Federer are tied at 20.

There’s also this on the line for Nadal in Sunday’s final against No. 8 Casper Ruud of Norway or No. 20 Marin Cilic of Croatia: It would be the first time the Spaniard ever has won the first two legs of the calendar-year Grand Slam.

Cilic won the 2014 U.S. Open; Ruud has never been to a major final.

Zverev was the runner-up at the U.S. Open two years ago and won a gold medal at the Tokyo Olympics last summer.

“I know how much he’s fighting to win a Grand Slam, but for the moment, he was very unlucky,” Nadal said. “The only thing that I am sure is he is going to win not one — much more than one. So I wish him all the best and a very fast recovery.”

Reporting by the Associated Press.