LONDON — After putting one shot into the net, Iga Swiatek muttered to herself. After another point went awry, she placed her hand over her mouth. Generally, she looked as flustered as she ever does on a tennis court.

Once again, she went from unbeatable on the French Open’s red clay to underwhelming on Wimbledon’s green grass.

The No. 1-ranked Swiatek’s 21-match winning streak ended with a listless performance and a slew of mistakes on Saturday, adding up to a 3-6, 6-1, 6-2 loss to unseeded Yulia Putintseva in the third round at the All England Club.

“Going from this kind of tennis, where I felt like I’m playing the best tennis in my life, to another surface, where I kind of struggle a little bit more, it’s not easy,” said Swiatek, who only once has made it as far as the quarterfinals at Wimbledon, exiting at that stage a year ago. “All that stuff really combines to me not really having a good time in Wimbledon.”

Never does. In 2022, for example, her 37-match unbeaten run was stopped with another third-round loss at the All England Club, that one to Alize Cornet.

Swiatek, a 23-year-old from Poland, is a five-time Grand Slam champion, including four titles at Roland Garros — most recently last month — and one on the hard courts at the U.S. Open. She has talked about looking forward to improving on grass, but she decided to withdraw last month from the only tuneup event that was originally on her schedule before Wimbledon.

Not that Swiatek thinks that was the issue against the 35th-ranked Putintseva.

On the contrary, Swiatek described herself as not giving herself enough of a chance to rest after the French Open.

“My tank of really pushing myself to the limits became, suddenly, empty,” she said. “I was kind of surprised.”

After a ho-hum first set, Swiatek faded against Putintseva, making mistake after mistake.

Swiatek not only won all four previous meetings against Putintseva, but also claimed every set they had played. Asked during a postmatch interview on No. 1 Court how she managed to emerge with the victory, the often-animated Putintseva replied: “I don’t know. Really, I don’t.”

Well, here is at least one key part of what happened: Swiatek looked very little like someone who has led the WTA rankings for nearly every week since April 2022 and is assured of remaining there no matter what happens the rest of the way at Wimbledon.

Still, this was her characterization of this week: “I felt like I underachieved a little bit. But it’s tennis, so you have to move on. I’ll have many more chances this year to show my game. I’ll just focus on that.”

Putintseva is on an eight-match run of her own, all on grass, including a title at Birmingham before arriving in London. This is the first time in 10 appearances at Wimbledon that the 29-year-old from Kazakhstan made it past the second round.

Her best showing at any Slam was getting to the quarterfinals at the French Open twice and U.S. Open once.

“I was playing fearless. I was just: ‘I can do it. I have to believe 100%. I have nothing to lose. Just go for it,'” Putintseva said at her news conference. “Also, my coach told me, ‘No matter which shot you’re doing, believe 100%.'”

When she was building a 4-0 lead in the last set by grabbing 16 of its first 19 points, Putintseva only needed to produce two winners. Her other 14 points in that span were gained thanks to either unforced errors (seven) or forced errors (seven) off Swiatek’s racket.

By the end, Swiatek had accumulated 38 unforced errors, more than twice as many as her opponent’s 15.

Next up for Putintseva is a matchup against 2017 French Open champion Jelena Ostapenko, who is seeded 13th. Also moving into the fourth round were 2022 Wimbledon champ Elena Rybakina, 2021 French Open winner Barbora Krejcikova, No. 17 Anna Kalinskaya, No. 21 Elina Svitolina and unseeded Wang Xinyu.

Svitolina advanced with a 6-1, 7-6 (4) victory over No. 10 Ons Jabeur, a three-time Grand Slam runner-up, including at Wimbledon each of the past two years.

The Associated Press contributed to this story.