LONDON — Coco Gauff said she was brought to tears by a “pushy” anti-doping tester. Serena Williams called the system ” grueling.”

Protocols designed to protect tennis from doping are in the spotlight as players open up about their experiences navigating the system in the aftermath of a four-year ban handed to 2023 Wimbledon champion Marketa Vondrousova — not for testing positive but for refusing to take a test.

Players are required to provide a 60-minute time slot each day to be available for testing, plus the International Tennis Integrity Agency says that if a doping control officer “locates and notifies a player outside of that hour, they must complete the test.”

Naturally, there’s a need for communication between players and testers.

“I’m not going to lie, some of them can be pushy, make you feel like you’re doing something wrong,” Gauff, the No. 7 seed, said after her first-round victory at Wimbledon.

“One time she came outside my time slot. But the way she was speaking to me on the phone, it literally made me cry afterwards,” the 22-year-old American said. “I found out I was in the right, and I didn’t have to do anything.”

Ahead of her first-round match, Ajla Tomljanovic described her close calls.

“I’m very scared of the system because it feels broken,” she said. “I’ve had a few experiences of my own where it was about technicalities and when I speak to people in charge they’re not helpful — I don’t want to say they don’t care — but they weren’t very helpful at all to explain things or just show some sort of compassion when I was nowhere near missing a test or testing positive.”

The Australian player said she was seeking help about how the app works.

“I was new to the whole system. And I was at two fails for a month and I knew if I get a third one accidentally I would be out for at least two, three years,” she said. “It’s in a way, I won’t say no fault of my own but it’s not to the degree of being banned and smearing your name. In that sense, I think there’s so much to improve on.”

Williams, who makes her Wimbledon return on Tuesday, said the testing system was “a big reason why I didn’t want to come back either, because it’s just so hard.”