Tiger Woods Supports Serena Williams at US Open — and Sits Next to Her Sister Venus in the Stands

Serena Williams is getting some support from the greats.

Serena, 40, is playing in the current US Open and revealed in a first-person essay for Vogue that she plans to step away from her 27-years-long professional tennis career after the tournament. Fans and friends are flocking to see her play, among them golf legend Tiger Woods.

Woods was spotted in Serena's personal box at the tournament, sitting next to her sister Venus Williams and cheering on his friend with a big smile that was shared by Venus.

The 46-year-old golf legend — in a hat, tee and jeans — was also sitting with girlfriend Erica Herman.

Serena revealed that, when she was considering leaving tennis, she turned to Woods for advice. Woods rose to prominence in professional golf around the same time Serena soared through the tennis world.

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"I said, 'I don't know what to do: I think I'm over it, but maybe I'm not over [tennis],' " Serena wrote in Vogue. "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.' "

Seth Wenig/AP/Shutterstock Venus Williams and Tiger Woods

Serena 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."

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"I was good. I was really good," Serena wrote of her comeback in Vogue. "I went back and forth about whether to play Wimbledon, and the US Open after that. As I've said, this whole evolution thing has not been easy for me."

Jamie Squire/Getty

RELATED: Serena Williams Went to Tiger Woods to Ask If She Should Retire: 'I Needed His Advice'

The tennis star won her first round at the US Open after she defeated Montenegro's Danka Kovinic, 6-3, 6-3. She won again against Anett Kontaveit of Estonia, the No. 2 seed, in the second round. This tournament will possibly be her final chance to capture her 24th Grand Slam victory and tie Margaret Court's record.

Many stars have supported Williams in what could be her final competition. Ahead of the start of the tournament, a Gatorade commercial dropped featuring longtime pal Beyoncé.

British director Jake Nava helmed the "Love Means Everything" ad, which aims to visualize "how Serena changed the game and inspired millions to love who they are and fuel their ambitions," even outside of tennis, the beverage company said.

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Hugh Jackman and his wife Deborra-Lee Furness also watched a match. Jackman, 53, shared a sweet photo of himself and Furness, 66, to Instagram on Monday.

"Off to the @usopen to watch the one and only @serenawilliams. Serena — Deb and I are so excited to watch you play and bear witness to your evolution for many years to come. You are an icon and a true inspiration to boys and girls around the world," he wrote, adding the fitting hashtag "#GOAT."

Former president Bill Clinton was in attendance with an unexpected guest: sex therapist Dr. Ruth Westheimer.

Rebel Wilson also attended, with girlfriend Ramona Agruma.