No. 2-ranked Iga Swiatek lost to a player younger than 18 for the first time on tour when she was stunned by Mirra Andreeva in the Dubai Championships quarterfinals Thursday.
Andreeva, 17, won 6-3, 6-3 to become the youngest semifinalist in Dubai's 24-year history and reach the first WTA 1000 semi of her career.
Thursday's loss for Swiatek follows a semifinal exit at the Qatar Open, a tournament she had won three straight years from 2022 to 2024.
"For sure it's a calendar thing. We're not going to be able to be consistent for many years playing week-by-week," Swiatek told reporters when asked whether playing back-to-back WTA 1000 tournaments was a tricky challenge. "Also it's not like some time ago that outside of top-20 players, they were just getting destroyed more. Now anybody can win these tournaments. It is like that since a couple of years."
Swiatek said her semifinal run at the Australian Open gave her less time to prepare for tournaments in the Middle East.
"I had the same kind of mindset as like every year. ... But the preparation for sure was different," she said. "Before, I lost in Australia early, so I had time to do some stuff. This year I didn't. Honestly, I'm not that direct usually, but I would blame this performance on the lack of practice before because I didn't have time.
"I'm not happy with the results. I feel like I underperformed. I need to talk with my team a bit and plan the next weeks a bit differently because I haven't had much time to practice before these tournaments."
Swiatek won their only previous match in August in Cincinnati, losing the first set and winning 7-5 in the third. She conceded the first again Thursday and was up a break in the second, but Andreeva reeled off the last five games, eventually sealing the victory when Swiatek's return on match point went wide.
"I was nervous before the match," said Andreeva, ranked 14th. "I told myself I played great in our last match and I just need to keep playing aggressive."
It's her fifth win over a top-10 player and second over a No. 2; she beat Aryna Sabalenka in the French Open quarterfinals last year.
Andreeva found herself on the ropes early as she struggled to hold serve in her first service game of the opening set but eventually held on to make it 1-1.
She then broke Swiatek and continued to impress, covering the court well while also reading her opponent's shots to set up winners. Andreeva broke Swiatek once more, firing a forehand return down the line on set point.
The Russian teen will next face sixth-seeded Elena Rybakina, who beat Sofia Kenin 6-2, 7-6 (2) to improve to 3-0 against the American.
Clara Tauson, who knocked out Sabalenka on Wednesday, defeated Linda Noskova of Czechia 7-6 (4), 6-4 to reach her third semifinals of the year. She will play Karolina Muchova, who eliminated Sorana Cirstea 6-2, 7-5.
The Associated Press and Reuters contributed to this report.