Rafael Nadal, with his win over Diego Schwartzman in the French Open semifinals Friday, improved to 99-2 at the tournament, including a combined 25-0 in semifinals and finals, as he seeks a fourth consecutive title in Paris. Christophe Ena/Associated Press

PARIS — Novak Djokovic seemed well on his way to yet another ho-hum victory, yet another French Open final, yet another matchup against rival Rafael Nadal. And then, suddenly, what had been a gallop became a grind.

Slightly more than two hours into his semifinal against Stefanos Tsitsipas on Friday night, Djokovic was serving for the match, one point from ending things in straight sets. But a down-the-line backhand veered a tad wide, Djokovic rolled his eyes and, eventually, he was stuck in a serious situation, somehow pushed to five sets.

As is usually the case, though, he was up to the task when it mattered the most. Djokovic got back in gear down the stretch to hold off the much younger, much less accomplished Tsitsipas 6-3, 6-2, 5-7, 4-6, 6-1 to reach his fifth title match in Paris.

Novak Djokovic celebrates after winning a point against Stefanos Tsitsipas in their French Open semifinal Friday in Paris. Djokovic won in five sets. Alessandra Tarantino/Associated Press

“Yes, I stayed calm on the surface, but deep down, it was a totally different matter,” Djokovic said. “But I think that when I lost the third set, I stayed mentally strong.”

Standing in the way of No. 1 Djokovic, a 33-year-old from Serbia, on Sunday at Court Philippe Chatier – he is pursuing a second trophy there and 18th from all Grand Slam tournaments – will be, as it’s been so often, No. 2 Nadal, a 34-year-old from Spain.

It will be their 56th meeting, a record between two men in the professional era (Djokovic leads 29-26), 16th at a major (Nadal leads 9-6) and eighth at Roland Garros (Nadal leads 6-1).

“It’s his house, with all the titles he’s won here,” Djokovic said.

In addition to closing in on an unfathomable 13th French Open championship with a 6-3, 6-3, 7-6 (0) win Friday over 12th-seeded Diego Schwartzman, Nadal now gets a chance to tie Roger Federer for the men’s record of 20 Slam titles.

As has been the case for quite some time, Nadal didn’t want to address the idea of pulling even with Federer, saying it’s fine for others to talk about such matters, but his focus remains squarely on the task at hand.

“I’m playing the most important tournament of the year – that’s what motivates me,” Nadal insisted.

In the women’s final Saturday, Sofia Kenin of the U.S. faces 19-year-old Iga Swiatek of Poland.

While Nadal only dealt with the slightest tension late in his third set Friday, that’s when everything became more interesting for Djokovic against Tsitsipas, a 22-year-old from Greece in his second Slam semifinal.

Djokovic broke to lead 5-4 in the third and served for the win, holding that match point at 40-30. He would require another 1 hour, 45 minutes to finish the job.

That one misstep left the door a bit ajar, and Tsitsipas barged through. He got his first break all match when Djokovic sent a forehand long, making it 5-all. Tsitsipas then broke again to steal that set and force a fourth when Djokovic netted a forehand.

Tsitipas then got things to a fifth set.

What changed? Tsitsipas began pushing forward more, taking the action to Djokovic, whose misses began to increase with less time to properly calibrate himself.

And there was a massive swing in who had greater success at key moments.

Djokovic started by converting 4 of 5 break points, then went through a stretch where he was 1 for 13.

Tsitsipas, in contrast, began 0 for 10 on his break chances, then cashed in 4 of 5.

A lengthy changeover after the fourth set – when Djokovic changed socks and shoes, and Tsitsipas got a medical visit for a check of his left leg – offered time to examine their respective histories in such situations.

Djokovic not only was 31-10 in five-setters, but he came into the day with a 215-1 record when taking the opening two sets of a Grand Slam match. Tsitsipas? He was 2-3 in five-setters, his only comeback from two sets down happening last week in the first round.

Maybe it made sense, then, that Djokovic, so reliant on drop shots all match and all tournament, used a perfect one to claim a 10-stroke exchange and finally get his fifth break for a 2-1 lead in the fifth. Then it became 4-1 when Tsitsipas double-faulted.

Djokovic never let up and is now 37-1 in 2020, the only setback coming via a disqualification at the U.S. Open last month.

Nadal improved to 99-2 at the French Open – go ahead, read that again – including a combined 25-0 in semifinals and finals, as he seeks a fourth consecutive title in Paris. That would add to his previous streaks of four in a row from 2005-08 and five from 2010-14, to go along with four trophies at the U.S. Open, two at Wimbledon and one at the Australian Open.

He has won all 15 sets he’s played over the past two weeks, making a mockery of the supposed explanations for why this year, so different for so many reasons, might be different for Nadal in the City of Lights.

The shift in dates from May-June to September-October, bringing cooler weather. New, slightly heavier, tennis balls. Nadal’s decision to skip the U.S. Open, leaving him with only three matches since tennis resumed in August. Then there was this: Schwartzman upset Nadal in straight sets on clay at the Italian Open last month.

“He improved,” Schwartzman said, comparing these past two encounters, “and I just played little bit worse.”

The late-afternoon sun at Court Philippe Chatrier created awkward shadows over much of the court and blinding brightness at one end, prompting Schwartzman to flip around his backward baseball hat so the brim could shield his eyes.

With the 5-foot-7 Schwartzman jumping to reach for two-handed backhands in reply to his formidable foe’s high-bouncing topspin forehands, Nadal was content as ever to engage in long, energy-sapping exchanges. The opening game required 14 minutes to complete merely 14 points, six of which lasted at least 10 strokes, with a high of 28, before Nadal held.

That established how things would go in that set: 22 of 69 points included double-digit shot counts. And Nadal’s 16-6 advantage in total winners in that set made the difference; the numbers were 38-24 by match’s end.

Only 1,000 spectators are being allowed on the grounds daily, owing to the rising COVID-19 cases in France, and the sparse crowd on hand was cheering for Schwartzman late in the third, likely not so much because they really were invested in a victory for him but because they wanted to watch more tennis.

By the end, fans were chanting, “Ra-fa! Ra-fa!” as they have so many times in the past.

“It’s important to go through all the process. You have to suffer. You can’t pretend to be in a final of Roland Garros without suffering. That’s what happened there,” Nadal said about the tight third set. “But I found a way, no?”

So, too, did Djokovic.