NEW YORK (PIX11) — Serena Williams upset No. 2 seed Anett Kontaveit of Estonia to advance to the third round at the U.S. Open.

Williams took the first and third sets to win 7-6 (4), 2-6, 6-2 in front of a record crowd of 29,959 fans at Arthur Ashe Stadium Wednesday night.

“This is what I do best. I love a challenge. I love rising to the challenge,” Williams said in her on-court interview after the match.

Williams, 40, has hinted that the U.S. Open could be the final tournament of her career.

“There’s still a little left in me,” the 23-time Grand Slam champion said.

Williams will play Ajla Tomljanović of Australia in the third round on Friday.