WIMBLEDON, England — In a Wimbledon tournament filled with early upsets, Reilly Opelka pulled off another one on Wednesday in the second round.
Opelka, a 6-foot-11 American with the big serve, defeated the three-time Grand Slam champion Stan Wawrinka, 7-5, 3-6, 4-6, 6-4, 8-6, on No. 2 Court.
“At first I had a lot of success serving and volleying, so I kept with that,” Opelka said. “And then as he kind of picked up on what I was doing and started reading my serve a little bit, it was more difficult for me to win points at the net. So I had to play, played a lot of tennis on the baseline today.”
Opelka is making his debut at Wimbledon, and playing in only his fourth Grand Slam tournament. He had never before reached the third round at any major. Wawrinka, who has won each of the other three major titles but has never been past the quarterfinals at the All England Club, also lost in the second round at Wimbledon last year.
On Monday, No. 6 Alexander Zverev and No. 7 Stefanos Tsitsipas were eliminated. No. 5 Dominic Thiem, a French Open finalist the past two years, followed them out of the tournament on Tuesday.
Opelka, 21, who is unseeded, finished the match against Wawrinka with 23 aces, with several serves topping 140 miles per hour. One, at 142 m.p.h., tied with Zverev for the fastest of the tournament so far.
“He went bigger than me and he deserved to win,” Wawrinka said.
Opelka will next face 15th-seeded Milos Raonic, the 2016 Wimbledon finalist, in the third round on Friday. He beat Robin Haase, 7-6 (1), 7-5, 7-6 (4).
The two-time major champion Victoria Azarenka, third-seeded Karolina Pliskova and eighth-seeded Elina Svitolina advanced in the women’s draw, but only two of them had an easy time getting to the third round.
Azarenka, who won the Australian Open title in 2012 and 2013, beat Ajla Tomljanovic, 6-2, 6-0, while Pliskova defeated the Olympic gold medalist Monica Puig, 6-0, 6-4.
Svitolina, on the other hand, was two points from losing to Margarita Gasparyan in the second set but eventually won when her opponent retired with an injury at 5-7, 6-5.
Gasparyan was serving at 5-5, 0-15 in the second set when she was injured. She clutched her right thigh after a serve and eventually dropped to the court, lying along the baseline. A trainer attended to Gasparyan, and Svitolina came over to check on her opponent, bringing her a bottle of water.
“I know when there is cramps you need to drink lots of water. Your muscles are contracting. So it’s important just to drink lots of fluids,” Svitolina said. “So that’s why I gave her some water, because no one really did anything. I mean, we were trying to help, but, yeah, it’s tough to react straightaway.”
When play resumed, Svitolina broke to lead by 6-5 and served for the second set, but Gasparyan retired from the match while trailing by 40-15 in that game.
The former No. 1 Simona Halep also advanced, beating Mihaela Buzarnescu, 6-3, 4-6, 6-2.