Serena Williams Relies On This $7 Waterproof Eyeliner, No Matter How Hard She's Sweating

Summer has officially arrived and dang did she come in hot. If you're breaking a sweat just thinking about the idea of wearing makeup in the heat, Serena Williams has a solution that's not only effective but affordable AF.

The Grand Slam boss recently chatted with The Strategist about her top can't-live-without-them essentials. She shared a few unique picks, including the Bible (which she reads daily, she said) and a "queen" necklace from her jewelry line that helps her "emulate a powerful, confident persona," she told the outlet.

For makeup, Williams said she likes to keep things simple given her busy schedule. "I do my makeup really fast every morning because I'm always in a rush," she told The Strategist. "I'm no pro, but it's been fun to learn new techniques from watching my favorite makeup artists over the years."

While Williams has drawn inspiration from her favorite MUAs, she said it was actually her physiotherapist, Beverly Hills-based Esther Lee, D.P.T., who first introduced her to her go-to eyeliner: Milani Stay Put Waterproof Eyeliner Pencil (Buy It, $7, amazon.com and target.com).

Available in five shades—Williams' favorites are black and espresso brown, but you can also choose from sapphire blue, slate gray, and plum purple—the eyeliner's waterproof gel formula delivers reliable staying power, while super-saturated pigments help your eyes pop. Voilà, a perfect way to play up your eyes sans smudge, especially if you're wearing face masks throughout the summer.

"I can wear this when I play tennis, and that's why I love it so much," Williams told The Strategist. "Other waterproof brands have just not been as reliable. This never wears off or budges, no matter how much I'm sweating."

Her sister, Venus, is also a fan of the waterproof eyeliner, added Serena. "We share makeup tips and product suggestions sometimes," she told The Strategist. (Another product Serena heard about through Venus: these bath salts she uses when she's sore.)

Reviewers agree with Serena and Venus: The drugstore waterproof eyeliner can handle the heat—even if you have oily skin. "I'm always looking for eyeliner that holds up on oily skin," wrote one reviewer. "I like this eyeliner a lot! It's great for everyday wear and doesn't turn into raccoon eyes halfway through the work day."

Another shopper said the waterproof Milani eyeliner pencil has been their tried-and-true for the last decade. "I've been using this eyeliner for over 10 years now, it is the best eyeliner I have EVER used!" they wrote. "It's bold and it doesn't smudge and I will never exchange it for another."

Ready to put the waterproof eyeliner to the (sweat) test? Shop the Williams sisters' pick below:

Buy It: Milani Stay Put Waterproof Eyeliner Pencil, $7, amazon.com and target.com