Day joins a growing list of—mostly male—athletes that are opting out of the Games, a trend that tennis pro Serena Williams called “sad” in an interview with USA Today.

“It’s probably one thing I have that I love the most,” Williams said to the news site. “It is really one of the best experiences that I’ve ever had.”

Still, Williams, who currently ranks as the top female tennis player in the world, says she gets why Day and other athletes are forgoing a trip to Brazil.

“At the same time, I obviously understand where they’re coming from and how they feel. Part of me feels that way, too, which is why I’m going in, you know, with a whole mindset of how do I protect myself, how do I prevent and also raise awareness for this,” she said.

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Williams, currently the world’s highest-paid female athlete, is one of few women in sports who can afford to miss the event. For many, performing on an international stage like the Olympics is too big of an opportunity to pass up—despite the health risks.