Simona Halep plays a shot against Amanda Anisimova during their quarterfinal match of the French Open at the Roland Garros stadium in Paris on Thursday. (AP photo)

By HOWARD FENDRICH

AP Tennis Writer

PARIS — Amanda Anisimova smacked one last backhand winner to complete her upset of defending champion Simona Halep in the French Open quarterfinals, flung her racket and covered her mouth with both hands.

Eyes wide, Anisimova then spread her arms with palms up and said, “What?!”

In a tournament filled with surprises, Anisimova provided the latest Thursday. Just 17 and ranked merely 51st, yet possessing the mindset and mien of someone much more experienced and accomplished, the American withstood a late charge by Halep and won 6-2, 6-4 to reach her first Grand Slam semifinal.

“I don’t think it will sink in, at least not for today. Yeah, I mean, it’s crazy,” said Anisimova, who was born in New Jersey to Russian parents and moved to Florida when she was 3. “I really can’t believe the result today.

“And getting the opportunity to play against Simona, that’s amazing. But how it ended is even crazier to me.”

That’s a fair assessment of the entire tournament. Serena Williams, No. 1 Naomi Osaka and No. 2 Karolina Pliskova lost in the third round; Angelique Kerber and Caroline Wozniacki were gone in the first.

The highest-seeded player in the semifinals is No. 8 Ash Barty, the Australian who will face Anisimova. Barty advanced by beating No. 14 Madison Keys of the United States 6-3, 7-5.

“I felt,” Barty said, “like I was in control.”

The other semifinal is No. 26 Johanna Konta of Britain against unseeded 19-year-old Marketa Vondrousova of the Czech Republic.

Because rain washed out all play Wednesday, the women’s semifinals — normally Thursday, one after another in the main stadium — were to be played simultaneously on the second- and third-largest courts this morning.

The biggest arena will host the men’s semifinals: Rafael Nadal vs. Roger Federer, and Novak Djokovic vs. Dominic Thiem.

It’s the first time the top four men’s seeds are the last four standing at a major tournament since the 2013 Australian Open.

Djokovic stretched his Grand Slam winning streak to 26 matches as he pursues a fourth consecutive major trophy, beating Alexander Zverev 7-5, 6-2, 6-2. Thiem eliminated No. 10 seed Karen Khachanov 6-2, 6-4, 6-2.

“Controlling the points was the key, I think,” said 2018 French Open runner-up Thiem, who made only 12 unforced errors, 25 fewer than Khachanov. “I didn’t miss a lot today.”