Iga Swiatek played like the current No. 1 and the two-time defending champion at the French Open. No surprise there. That Naomi Osaka looked like the former No. 1 that she is — and on clay, no less — amounted to an announcement that she is still quite capable of elite tennis.

Surging down the stretch as Osaka faded, Swiatek saved a match point and grabbed the last five games to sneak her way to a 7-6 (1), 1-6, 7-5 victory in the second round of the French Open on Wednesday night in a thrill-a-minute contest befitting two women who both own four Grand Slam titles.

"For sure, this match was really intense. Much more intense for the second round than I ever expected. For sure, I'll be more ready next time," Swiatek said. "Naomi played amazing tennis. … I'm happy that she's back and she's playing well."

For Swiatek, this extended her Roland Garros winning streak to 16 matches as she pursues a third consecutive trophy at the clay-court major. For Osaka, who cried when she left the court after letting a 5-2 lead in the concluding set slip away, this amounted to a return to her big-hitting best.

They went back-and-forth for nearly three hours as rain loudly pelted the outside of the closed roof at Court Philippe Chatrier — showers forced the postponements of 23 singles matches until Thursday — and a riveted, if hardly full, crowd alternated their support between the two players. Sometimes, spectators called out before a point was done, prompting admonishment from chair umpire Aurelie Tourte during the match. And from Swiatek afterward.

"Sometimes, under a lot of pressure, when you scream something during the rally or right before the return, it's really, really hard to be focused," Swiatek said. "The stakes are big and there is a lot of money here to win. So losing a few points may change a lot. So please, guys, if you can support us between the rallies but not during, that would be really, really amazing."

Osaka served for the victory at 5-3 in the final set, and was a point away from winning, but she put a backhand into the net. Soon, when Osaka missed another backhand, this one long, Swiatek finally converted a break point on her 10th chance of that set, and they played on.

Maybe the lack of high-level matches caught up to Osaka, because her mistakes continued to mount, including a double-fault that put Swiatek in control 6-5. Swiatek, who has led the WTA rankings for nearly every week since April 2022, then held serve one last time.

"I don't necessarily feel like I regret anything," Osaka said.

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Still, this was, without a doubt, Osaka's top performance since she returned to the tour in January after 15 months away while becoming a mother. (Her daughter, who is 10 months old now, accompanied Osaka to Paris and recently started walking.)

"I was watching Iga win this tournament last year, and I was pregnant. It was just my dream to be able to play her," Osaka said. "When I kind of think of it like that, I think I'm doing pretty well. And I'm also just trying not to be too hard on myself. I feel like I played her on her better surface. I'm a hard-court kid, so I would love to play her on my surface and see what happens."

Because of the weather, only nine matches were completed Wednesday, and winners included Coco Gauff, Ons Jabeur, Sofia Kenin, Carlos Alcaraz, Stefanos Tsitsipas and Andrey Rublev.

It's been a few years since Osaka played this capably and confidently, hammering big serves at up to 197 kilometres per hour and imposing groundstrokes. Her quick-strike capabilities were on full display: Osaka won 82 of the 139 points (59 per cent) that lasted four strokes or fewer, and she finished with a 54-37 advantage in total winners.

All of those familiar mannerisms were back, too. She turned her back to Swiatek to reset between points, hopped in place, tugged at her pink visor's brim and slapped her palm on her thigh. Osaka celebrated points by shaking a clenched fist and shouting "Come on!"

She grabbed nine of 10 games to dominate the second set and lead 3-0 in the third. Then 4-1. Then 5-2.

As one ball or another would fly past Swiatek, zipped near a corner or right at a line, she turned toward her guest box and shot a look of confusion or concern in the direction of her coach and her sports psychologist.

"I felt for most of the match that I wasn't really [in the] here and now," Swiatek said. "My mind was, like, playing around sometimes."

She's not used to this sort of one-way traffic coming head-on in her direction. Normally, it's Swiatek who is delivering lopsided sets at a foe's expense, especially on clay. She now has won her last 14 matches this month, with titles on the surface at Madrid and Rome — a clay double no woman had done since Serena Williams in 2013.

But this marked a sudden return to the Osaka everyone came to expect, match in and match out, back when she was at the height of her powers, climbing atop the rankings and gathering two trophies apiece at the U.S. Open and Australian Open from late 2018 to early 2021.

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It was in May 2021 that Osaka withdrew from the French Open before her second-round match, explaining that she experiences "huge waves of anxiety" before speaking to the media and revealing she had dealt with depression. She took time away from the tour for a mental health break, then opted for another hiatus after her title defence at the U.S. Open a few months later ended with a third-round loss.

She helped usher in a change in the way athletes, sports fans and society at large understood the importance of mental health — and prompted those in charge of various sports, including tennis, to take the issue seriously and try to accommodate and protect them better.

Osaka entered with an 0-4 record on the red stuff against opponents ranked in the top 10 and never has been past the third round at Roland Garros. This also would have been her first win anywhere against a top-10 opponent since January 2020.

Instead, though, it is Swiatek who moves on and continues her bid to become the first woman with three championships in a row in Paris since Justine Henin in 2007-09.