Williams share another image on Instagram, in which she wears yet another small one-piece ― this one by American Apparel ― that matches the crystal blue waters behind her.
Williams is no stranger to the pages of Sports Illustrated, earning its Sportsperson of the Year title in 2015. But there is something new happening: Williams revealed in a behind-the-scenes video that the shoot marked her first time ever wearing a thong bikini.
"I'm officially a thong girl now," she said.
It makes sense that Williams is once again featured in the swimsuit issue, which includes many different inspiring women, including her fellow tennis stars Caroline Wozniacki and Genie Bouchard, fellow uber-athlete Simone Biles, and model Ashley Graham.
Head to Sports Illustrated to see a slew of gorgeous images of Williams.