AP photo by Michel Euler / Novak Djokovic celebrates after beating Matteo Berrettini in their French Open quarterfinal Wednesday night in Paris.

PARIS — Novak Djokovic wheeled toward his guest box in a nearly empty Court Philippe Chatrier as midnight neared and let out one yell, two yells, three yells, four.

Once two points from winning in straight sets and seemingly well on his way to a French Open semifinal showdown against 13-time champion Rafael Nadal, the 34-year-old Serbian had to deal with so much that went awry Wednesday night: consecutive unforced errors that gave away a tiebreaker; a 21 1/2-minute delay as spectators left because of a COVID-19 curfew; a face-down tumble that drew blood from his left palm.

Still, the top-seeded Djokovic held on and moved on, pulling out the quarterfinal victory against No. 9 Matteo Berrettini of Italy, 6-3, 6-2, 6-7 (5), 7-5.

"This match had it all: falls, crowd, break. It was a lot of intensity. I just felt under tension the entire time," Djokovic said. "The reaction (at) the end was just me liberating that tension that was building up for the entire match."

Next up is a familiar foe and a rematch of last year's final, but a round earlier: No. 3 Nadal, who improved to 105-2 in the clay-court tournament with Wednesday's quarterfinal win against 10th-seeded Diego Schwartzmann of Argentina, 6-3, 4-6, 6-4, 6-0.

Said Nadal, who's seeking a record-breaking 21st Grand Slam men's singles title, of the semifinal showdown: "We know each other well. Everybody knows that in these kind of matches, anything can happen."

The 35-year-old Spaniard dropped a set at Roland Garros for the first time in two years but reached his 14th semifinal in Paris, punctuating his latest quarterfinal victory with violent forehands, fist pumps and shouts of "Vamos!"

"For anybody, it's very difficult to play against him. He's feeling very comfortable on court," Schwartzman said after falling to 1-11 against Nadal. "He's Rafa, and he's always finding the way."

The other men's semifinal Friday pits No. 5 Stefanos Tsitsipas of Greece, who is 22, and No. 6 Alexander Zverev of Germany, 24.

It's Djokovic's 11th French Open semifinal and 40th trip to the final four at any major (it's Nadal's 35th). Nadal and Roger Federer, who withdrew from the tournament Sunday after a victory, share the men's singles mark of 20 Grand Slam titles; Djokovic is at 18. The semifinal will be the superstar duo's 58th matchup, more than any other two men in the sport's professional era; Djokovic leads 29-28, but Nadal is ahead 10-6 in Slam meetings, including 7-1 in Paris

"I'm confident. I believe I can win," Djokovic said. "Otherwise, I wouldn't be here."

Djokovic was so close to advancing when he led the third-set tiebreaker against 2019 U.S. Open semifinalist Berrettini 5-4. But after accumulating merely 14 unforced errors over some 2 1/2 hours up to then, Djokovic committed two in a row — a nervy forehand into the net, then a backhand into the net — and lost that set, drawing roars from a crowd hoping for more tennis.

The number of people allowed in the 15,000-seat main stadium was limited to 1,000 for each of the first 10 days of the tournament because of coronavirus pandemic-related restrictions, but that limit was raised to 5,000 on Wednesday. The start of play for Djokovic-Berrettini was bumped up an hour to 8 p.m., and the 9 p.m. curfew that had been in place was moved to 11.

They did the wave, added some atmosphere and kept chair umpire James Keothavong a bit busy — especially when it was time to empty the stadium.

When the curfew arrived, there were jeers and whistles and some slow movers, so Djokovic and Berrettini — who seemed particularly buoyed by the prodding he received from fans — gathered their belongings and left the court until the match could resume. Berrettini said that when action returned, his legs felt like they were "made of marble."

"It's a shame. It's something that I don't like," he said about the delay, adding that he understood the need for special rules during the pandemic.

Berrettini didn't play a point in the fourth round because the player he was supposed to face, Federer, withdrew with an eye to being ready for Wimbledon. In Djokovic's previous match, he dropped the first two sets against another Italian, 19-year-old Lorenzo Musetti.

Sure, Berrettini produced a trio of break points in the opening set Wednesday, but he converted none and never earned another such chance. Djokovic needed to do a little extra work to finish the job, though.

Nadal, meanwhile, entered his quarterfinal with a 35-set run at Roland Garros that began during the 2019 final. That grew to 36 before Schwartzman outplayed him for a stretch.

Tied at a set apiece and with Schwartzman up 4-3 in the third, this is how Nadal sized things up: "That was the moment to make it happen."

As if wanting something were enough to will it into existence, he won the next nine games, leaving Schwartzman muttering to himself and bouncing his racket off the clay.

"The thing that matters is how you recover from a set lost," Nadal said.

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AP photo by Thibault Camus / Coco Gauff eyes the ball as she plays Barbora Krejcikova in a French Open quarterfinal Wednesday in Paris.

The women's semis are also set after Maria Sakkari beat Iga Swiatek 6-4, 6-4 — ending 11-match and 11-set winning streaks for the 2020 French Open champion — and Barbora Krejcikova defeated American teen Coco Gauff 7-6 (6), 6-3.

On Thursday, the 17th-seeded Sakkari, a 25-year-old from Greece, faces unseeded Barbora Krejcikova of the Czech Republic, also 25, while No. 31 Anastasia Pavlyuchenkova, 29 and from Russia, faces unseeded Tamara Zidansek, 23 and from Slovenia.

This is only the second time in the professional era there have been four first-time semifinalists at any major tournament, according to the WTA; it also happened at the 1978 Australian Open.

"We are four very good players," Sakkari said. "Players that can win a title, for sure."

In the day's first quarterfinal, Gauff led 3-0 at the outset, then 5-3, and she held a total of five set points in the opener but failed to convert any. Krejcikova grabbed that set by taking the last four points of the tiebreaker and reeled off 15 consecutive points during one stretch en route to a 5-0 edge in the second set.

Closing out the most important victory of her singles career was not easy, though: Krejcikova needed six match points to do it.

Gauff's 41 unforced errors included seven double faults, and after one, she mangled her racket frame by whacking it three times against the ground.

"My hitting partner told me this match will probably make me a champion in the future," the 17-year-old said. "I really do believe that."