Serena Williams' hopes of a victorious return to the Wimbledon Championships after a year away from professional tennis ended with a shock first round 7-5, 1-6, 7-6(7) defeat to France's Harmony Tan in a three-set thriller on Centre Court in London on Tuesday.

In the longest match of the tournament thus far, Tan twice came back from a break down in the third set to notch just the third major main-draw win of her career.

"I am so emotional now. I don't know how to say now, because it's a superstar and when I was young, yeah, watching her so many times on the TV. For my first Wimbledon, it's wow, just wow." Tan said afterward.

"I think physically I did pretty good," said Williams, the 23-time grand slam champion. "I think the last couple of points, I was really suffering there."

The former world No.1's previous singles match took place one year ago on the very same court, where she suffered an ankle injury against Aliaksandra Sasnovich in the first round.

The seven-time Wimbledon title holder suffered only her third first-round loss at a grand slam event in her legendary career. Her win-loss record at Wimbledon stands at a staggering 98-14.

At 40, the American's time in the game is clearly running out, but she remained vague about her future plans and refused to rule out another tilt at Wimbledon next year.

"Like I said coming into this, I'm just planning for right now, seeing how I feel, just to go from there," she said.

Also on Tuesday, China's Zheng Qinwen clinched her first Wimbledon win. The 19-year-old, who was the only player to take a set off winner Iga Swiatek at the 2022 Roland Garros, knocked out 2017 U.S. Open champion Sloane Stephens 7-6(1), 7-5 in 1 hour and 43 minutes.

(With input from AP and WTA)