Garbiñe Muguruza, who beat Serena Williams in French Open final, loses in second round at Wimbledon

After two days filled with rain, the sun actually made an appearance at Wimbledon on Thursday, allowing for plenty of play all around the grounds, a chance to finally conclude the first round — and several surprises, the biggest of which was French Open champion Garbine Muguruza’s exit.

No. 2 Muguruza, who reached her first Grand Slam final at the All England Club a year ago and won her first Grand Slam title less than a month ago, was one of 18 seeded players who lost on Day 4, including 11 women.

Admittedly lethargic, and displaying none of the verve or confident shotmaking she’s known for, Muguruza lasted less than an hour in the second round Thursday, beaten, 6-3, 6-2, by Slovakia’s Jana Cepelova, a qualifier ranked 124th.

“My energy was not really there,” Muguruza said. “I was trying, but [it] didn’t work at all.”

That same sentiment might have been expressed by some of the other players who joined her on the way out of the tournament, including No. 31 Kristina Mladenovic in a weather-delayed first-round match, and No. 7 Belinda Bencic, No. 14 Sam Stosur, No. 15 Karolina Pliskova, No. 16 Johanna Konta, No. 17 Elina Svitolina, No. 20 Sara Errani, No. 22 Jelena Jankovic, No. 30 Caroline Garcia and No. 32 Andrea Petkovic, all in second-round matches.

That group includes a Grand Slam champion (Stosur), major finalists (Errani, Jankovic), the first seeded British woman at Wimbledon since 1984 (Konta, eliminated by 2014 runner-up Eugenie Bouchard) and a top-10 player considered a possible future star of the sport (Bencic, who retired because of a left wrist injury while trailing American qualifier Julia Boserup).

There was nearly another big name gone. But No. 3 Agnieszka Radwanska, the 2012 Wimbledon runner-up, saved three match points, then took advantage when her opponent, 18-year-old Ana Konjuh of Croatia, twisted her right ankle by accidentally stepping on a tennis ball during a point. That happened at 7-all in the third set and, although Konjuh continued to play after a medical timeout, Radwanska was able to finish off a 6-2, 4-6, 9-7 victory.

The seven seeded men who lost, all in the second round, were No. 8 Dominic Thiem, No. 13 David Ferrer, No. 16 Gilles Simon, No. 23 Ivo Karlovic, No. 25 Viktor Troicki — who launched an epic tirade at the chair umpire because of a call two points from the end of his five-set defeat — No. 26 Benoit Paire and No. 30 Alexandr Dolgopolov.

Muguruza was never able to get going, making 22 unforced errors and managing to produce only nine winners.

She said she felt tired and on the verge of an illness.

She also wished she had taken more time to rest after the grueling two weeks at Roland Garros that culminated with a victory over Serena Williams in the final.

Asked whether coming into Wimbledon as the owner of a major trophy made her feel a weight on her shoulders, Muguruza replied: “No, not pressure. I think, for sure, more expectations from other people.”

“Honestly, for me, I just had very clear it was going to be a rough tournament for me after winning a Grand Slam and coming here,” she continued. “Everybody, you know, like, looking at me.”

Cepelova equaled her best showing at a major by reaching the third round, but this was not her first significant result. She beat Simona Halep in the first round at Wimbledon a year ago, also on No. 1 Court, and defeated Serena Williams at a tournament in Charleston, S.C., in 2014.

“Yeah,” Cepelova said, “I like to play on the big courts.”

As the owner of seven Grand Slam singles titles, including five at Wimbledon, Venus Williams is accustomed to being — and succeeding — on those stages. But on Thursday, she found herself on Court 18, with its seating capacity of 782 — a far cry from the nearly 15,000 at Centre Court.

Williams, seeded eighth, had some trouble and needed 21/2 hours, but wound up getting past 20-year-old qualifier Maria Sakkari, 7-5, 4-6, 6-3 — one of 10 singles victories for Americans on Thursday.

Afterward, Williams did not complain about her placement at that venue. But she did offer some thoughts on the topic.

“It’s not the ideal schedule for the women. We’d like to see equal amount of matches. We don’t want more, just the same amount, that’s all,” said Williams, who was a leading voice in the push to get Wimbledon to offer equal prize money to men and women.

Asked whether she could imagine a five-time men’s champ being on a smaller court, Williams replied: “I haven’t seen that in the scheduling yet.”