MADRID -- Tennis players are facing an unknown opponent at the Madrid Open.
A stomach virus or food poisoning has affected Coco Gauff, Marin Cilic and a few others, causing some concern.
World No. 1 Aryna Sabalenka avoided an upset by Naomi Osaka on the court on Monday and said she's trying to avoid illness by sticking to a simple diet of chicken breast, rice and salad.
The rumor among the players was bad shrimp tacos were to blame.
Sabalenka knocked on wood and said, "So far, so good. I heard that I have to avoid those tacos (laughing). I stick to the same food, same meal that I've been having since the very beginning of the tournament."
Sabalenka said she was spending as little time as possible on site at the Caja Magica tennis complex.
"I try not to stay for too long," she said. "Extra vitamin C, I guess, extra IM8, and I'm good to go, hopefully."
Gauff vomited on the court on her way to a victory over Sorana Cirstea on Sunday. The American didn't show signs of illness on Monday in her 6-4, 1-6, 7-6 (5) loss to Linda Noskova, last year's runner-up to Sabalenka.
Cilic couldn't play his match against João Fonseca on Friday.
"Unfortunately, I got food poisoning," Cilic said. "After trying to recover all night my body is unfortunately exhausted and not at the proper level to get into the battle."
Sabalenka rallies
Sabalenka rebounded from a set and a break down against Osaka in their fourth round contest.
She prevailed against No. 15 Osaka 6-7 (1), 6-3, 6-2 in 2 hours, 20 minutes to reach the quarterfinals and stay on track to defend her title.
"Oh my God, that was an incredible level," Sabalenka said. "She played incredible tennis. I feel like I just got lucky in a couple of shots in the third set, that's why it went that fast. I'm happy she brought that fight, I had to fight through to level up my game."
Sabalenka won her 15th straight match and advanced to her 17th consecutive quarterfinal. She hasn't lost before that round since February 2025 in Dubai. The Belarusian said her team kept pushing her to "keep fighting, keep going."
"I'm really happy that I didn't give up and I was pushing until the very last point," Sabalenka said.
Longest tiebreaker since 2024
Sabalenka will next face American Hailey Baptiste, who defeated Belinda Bencic 6-1, 6-7 (14), 6-3 after losing the second set in the longest tour-level regular tiebreaker since 2024, according to the WTA.