The 43-year-old Williams defeated Russian Veronika Kudermetova 6-4 7-5 in the first round of the Western & Southern Open in Cincinnati on Monday.
Kudermetova is seeded 16th in the tournament and would have been expected to ease her way past Williams, but the seven-time grand slam winner had other ideas.
“Definitely satisfaction from today is (from) all the work that goes into just being here at all,” the veteran American said after the win.
“I did my best to be here as soon as possible in the best form possible I could bring in that amount of time. So that makes it satisfying, to be able to get a win with very little time to prepare.”
In both sets, Williams found herself 4-1 down and on the back foot, but, as on so many occasions throughout her career, she found a way to battle back.
“I think at some point when you’re down a double break, you start to think, ‘Well, I at least want to just hold serve for the rest of this set,’” Williams said. “Simple thoughts like that. Then you get a little bit closer. You’re like, ‘Okay, maybe I just want to win another point.’
“Definitely some big holes today that I usually don’t play from … But that’s tennis. That’s what’s so exciting.”
Williams will now wait to see who she faces in the next round in Cincinnati as she continues her preparation ahead of the 2023 US Open.
Her previous victory against a top-20 opponent also came at the Western & Southern Open in 2019 when she defeated Kiki Bertens in the second round.