Serena Williams stormed back in the third set to defeat No. 2 world-ranked Anett Kontaveit in the second round of the U.S. Open in what is likely the final Grand Slam tournament of her career.

Williams was asked after the match what changed for her when she came out of the bathroom break before the final set. The reporter noted that Novak Djokovic may go into the bathroom to splash water on his face or give himself positive affirmations to finish up his match.

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The legendary tennis star painted a different picture.

"I just got lighter," Williams said with a laugh. "Use your imagination. But it wasn’t number two so …"

Williams dominated the third and final set, 6-2, after Kontaveit won by the same score in the second set. She came out firing in the third set, getting the first two games to go in her favor. After Kontaveit took the third game on a breakpoint, Williams returned the favor and then won the fifth game, giving herself a commanding 4-1 lead. 

SERENA WILLIAMS UPSETS NO. 2 ANETT KONTAVEIT, ADVANCES TO NEXT ROUND OF US OPEN

Kontaveit would win the next game, but it would be all Williams from there, dominating to a 6-2 victory as she was showered by the roars of fans in Queens. 

"I'm loving this crowd," Williams said smiling after the match. 

"Oh my goodness, it’s really fantastic. There’s still a little left in me. We’ll see."

Williams will hope to prove she has still got some in the tank in the third round against Australia's Ajla Tomljanovic, who beat Evgeniya Rodina in three sets at a separate court on Wednesday night. 

Fox News’ Scott Thompson contributed to this report.