The tennis icon, 40, says having the legendary golfer, 46, in her corner — and in her player's box Wednesday night during her second-round US Open match versus Anett Kontaveit — made all the difference.
"Yeah, he's one of the reasons I'm here, one of the main reasons I'm still playing," the 23-time Grand Slam title winner said after the match of Woods. "So we talked a lot. He was really trying to get me motivated. There's a few people, but we were like, 'Okay, we can do this together,' you know?"
She continued, "It was good, because I didn't know what I wanted to do … was just lost, so many questions. When you can rely on someone like that, I mean — my goodness, he's Tiger Woods — it was really helpful to get clarity."
The feeling was mutual for Woods, who tweeted his appreciation shortly after Williams' thrilling upset.
"It was a privilege to watch greatness. Congrats @serenawilliams," he wrote.
In her essay in the September issue of Vogue, the tennis star shared how she came to make her decision to "evolve" away from the sport, and said a conversation with Woods helped to give her direction.
Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.
Stephane Cardinale/Corbis/Getty; Andrew Redington/Getty
"I said, 'I don't know what to do: I think I'm over it, but maybe I'm not over [tennis],' " Williams wrote. "He's Tiger, and he was adamant that I be a beast the same way he is! He said, 'Serena, what if you just gave it two weeks? You don't have to commit to anything. You just go out on the court every day for two weeks and give it your all and see what happens.' I said, 'All right, I think I can do that.' "
Williams wrote that she waited one month before taking Woods' advice and returning to the court, saying that it "felt magical to pick up a racket again."
Now, the magic continues to the third round, when Serena will face Ajla Tomljanovic of Australia on Friday night.