Serena Williams "gave all I could" in an epic first-round Wimbledon defeat to Harmony Tan and could not assure fans she would be back on Centre Court again.

Williams is a seven-time Wimbledon champion – only Martina Navratilova has won the championships on more occasions in the Open Era – but her last championship victory came back in 2016.

There have been two final appearances since then but also now consecutive first-round exits, having retired with a hamstring tear against Aliaksandra Sasnovich in 2021; previously in her remarkable career, Williams had fallen at the final hurdle only once at any major.

Tuesday's battle with Tan was her first singles match since that injury, and Williams certainly did not lack spirit, recovering from losing the first set to dominate the second and then take control of the third, too.

Twice in the decider she led by a break, attempting to serve for the match at 5-4, only to be broken back.

Williams was then required to hold serve – and fend off a match point – to reach a tie-break, in which she led 4-0.

But Tan reeled off the next five points and eventually prevailed 7-5 1-6 7-6 (10-7) from the sort of titanic tussle Williams – now 40 and "really suffering" by the end – may not see again.

"That's a question I can't answer," she replied when asked if this was her last Wimbledon appearance. "I don't know. Who knows where I'll pop up?"

Williams "obviously" did not want this to be her lasting memory of the grass-court major. "You know me," she said. "Definitely not."

But the American added: "I gave all I could do. Maybe tomorrow I could have given more. Maybe a week ago I could have given more. But today was what I could do.

"At some point, you have to be able to be okay with that."

However, while her Wimbledon future is clearly in doubt, Williams appeared to suggest a US Open tilt later this year was highly likely.

"When you're at home, especially in New York and that being the place I first won a grand slam, it is always special," she said.

"There's always motivation to get better and play at home."