Jamie McCarthy/Getty Images for Glamour
The professional tennis star presented Gigi with the Supernova Award during Monday night's 2017 Glamour Women of the Year Awards in New York City, revealing just how tight their bond really is.
"Gigi," Serena shared onstage, "you are one of the few people on this planet I would leave my baby for—for one night—but for you it shows how much you mean to me. And I want you to imagine the affect you have on the world."
Williams, who welcomed daughter Alexis Olympia Ohanian Jr. with fiancé Alexis Ohanian in September, continued gushing, "She understands that in order to be the best, you have to think like you are the best, work the hardest, and make sacrifices... Gigi pushes boundaries. In fact, she makes new boundaries. And she's authentically herself."