Serena Williams turned to Tiger Woods for his input before she made her recent comeback from a year-long injury absence. On Thursday, Woods sat courtside at the US Open, throwing uppercuts in the stands to cheer Williams on to victory.

"He's one of the reasons I'm here," Williams said after beating No. 2 seed Anett Kontaveit 7-6 (4), 2-6, 6-2 to reach the third round at Flushing Meadows in what could be the last tournament of her career. "One of the main reasons I'm still playing."

Woods was in Williams' guest box at sold-out Arthur Ashe Stadium, two seats over from her sister, Venus.

When Woods was shown on the overhead video screens during a break between games, he received a warm welcome from the crowd and tugged at the brim of his cap to acknowledge the applause.

After the match, Woods tweeted: "It was a privilege to watch greatness. Congrats @serenawilliams"

Three weeks ago, 23-time Grand Slam champion Williams announced she was getting ready to walk away from her playing days via an essay in Vogue magazine. In the piece, she said she approached Woods — the owner of 15 golf majors who returned to action after badly damaging his leg in a car crash — for advice when she was trying to figure out whether to return to playing after she was sidelined by an injury at Wimbledon in June 2021.

"He's Tiger," she wrote, "and he was adamant that I be a beast the same way he is!"

Asked Thursday about Woods' role, Williams said: "We talked a lot. He was really trying to get me motivated."

She continued: "I didn't know what I wanted to do. I 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."

Serena Williams celebrates her remarkable upset victory at the US Open. Photo / AP

After Thursday's win, Williams boasts a 23-2 record in her last 25 matches against players ranked in the top two, a run that dates back to 2007.

"I'm not in any rush here (to leave)," Williams proclaimed after the triumph.

"I'm loving this crowd, and there's still a little left in me. We'll see.

"This is what I do best, I haven't played many matches but I have been practising really well. The last couple of matches in New York it's really come together."

When asked whether she was surprised at her playing form, Williams replied with an answer that hinted at the kind of words Woods may have passed onto her: "I'm just Serena, you know?

"I'm just looking at it as a bonus, I have nothing to prove … I have nothing to lose.

"I haven't been able to play like this since 1998, I've had an X on my back since 1999."