Serena Williams is 42-0 in the first two rounds of the U.S. Open. (Al Bello/Getty Images)

Serena Williams was never going to fade into the background, but few could’ve predicted the spectacular performance the 40-year-old put on to topple No. 2 Anett Kontaveit in the second round of the US Open Wednesday night.

“I’m a pretty good player. This is what I do. I love a challenge, and I’m rising to the challenge,” Williams said following her thrilling 7-6 (7-4), 2-6, 6-2 victory over the 26-year-old Estonian star.

When asked if she surprised herself with her level of play, Williams simply replied, “I am just Serena.”

Vintage Serena was on full display Wednesday, energizing a raucous crowd at Arthur Ashe Stadium. Fans poured into Flushing Meadows to catch a glimpse of what is expected to be Williams’ final US Open ahead of her impending evolution away from tennis.

The 29,959 fans who showed up to Billie Jean King National Tennis Center broke the all-time night-session attendance record — which had been set two nights earlier, when 29,402 showed up for Williams’ opening match.

Williams’ iconic serve helped her in crucial moments. She fired 11 aces to clinch a hard-fought match that extended beyond the two-hour mark.

Kontaveit was a worthy opponent, at times drawing Serena off the court with a powerful baseline game. Williams, however, rose to the occasion, finding her openings and making them count.

“I think she played really well,” Kontaveit said after the match. “I mean, I thought I didn’t play a bad match at all. She definitely raised her level in the third set. She played amazing.”

Williams prevailed on a day where several top seeds faltered, including No. 3 Maria Sakkari, who Williams was projected to face in the semifinals should she advance that far. She now would be projected to face No. 12 Coco Gauff.

With upsets aplenty, Williams’ once-tough road through the bracket looks much more manageable as she heads to the round of 32. She wouldn’t go up against a seeded player until the quarterfinals, when she would be in line to face No. 5 Ons Jabeur if seedings hold true.

First, though, Williams will face No. 46 Ajla Tomljanović in the third round Friday. The Australian downed Evgeniya Rodina in a three-set battle to earn a meeting with Williams, who she has yet to face in her career.

While all eyes will be watching for Williams to continue her final run, the six-time US Open champion insists this campaign is simply icing on the cake.

“I don’t have anything to prove. I don’t have anything to win. I have absolutely nothing to lose,” Williams said.