Serena Williams left her Australian Open news conference in tears after her semi-final defeat by Naomi Osaka.
The American great saw her latest bid for a record-equalling 24th Grand Slam title ended by Japan's three-time major champion Osaka, who won 6-3 6-4.
She gave the crowd inside Rod Laver Arena a long wave goodbye with her hand over her heart, leading to questions over the 39-year-old's future.
She responded: "I don't know. If I ever say farewell, I wouldn't tell anyone."
Williams became tearful when asked a further question about her unforced errors against Osaka.
"I don't know. I'm done," she said, before leaving the room.
- Live scores, results and order of play
- Osaka beats Williams to reach final
- Alerts: Get tennis news sent to your phone
Williams thanked her fans in a post on Instagram shortly after the match.
"Today was not ideal outcome or performance but it happens. I am so honoured to be able to play in front of you all," she wrote.
"Your support, your cheers, I only wish I could have done better for you today.
"I am forever in debt and grateful to each and every single one of you."
'Wimbledon is Williams' best chance'
Williams has been aiming to equal Margaret Court's major record since her return from maternity leave in 2018.
Her 23 Grand Slam titles is the most by any player in the Open Era, with 13 of Court's titles coming before the tour became fully professional.
Since her return, Williams has reached four Grand Slam finals but lost them all, including to Osaka at the 2018 US Open.
Former British number one Annabel Croft says Wimbledon, where Williams has won eight titles, is her best chance to equal Court's record.
"Serena seemed to be in a happy place and I was thinking this is it - this is the time she is going to win her 24th," Croft told BBC Radio 5 Live.
"Time is not on her side, though. You have to marvel at well she is playing considering there is such a huge difference in age against some of her opponents.
"The draw would weirdly have to open up for her [to win] but it is not beyond the realms of possibility."
It is the first time in 18 years that Williams has lost an Australian Open semi-final.
It is also her first loss against a top five opponent at a hard court Grand Slam since she was beaten by Jelena Jankovic in the Australian Open last 16 in 2008.
Osaka, who has often spoken of her admiration for Williams, said talk of the American retiring made her "sad".
"I want her to play forever," Osaka said. "That's the little kid in me.
"Every time I play her, I feel like it's something I'll definitely remember a lot."
Novak Djokovic, the men's number one and a 17-time Grand Slam champion, said he could "empathise" with Williams.
After reaching the final in Melbourne, the 33-year-old Serb is one more win from closing the gap on Roger Federer and Rafael Nadal, who jointly hold the men's record of 20 major wins.
"When you're chasing big things that are related to the history of the sport, obviously it has a lot of weight, a lot of pressure," he said.
"Regardless of the amount of years that you have played on the tour and the experience that you have, you still feel it on your shoulders.
"I'm proud and honoured to be playing at the same time she does and to experience her greatness is a thrill. She's one of the greatest athletes ever."
- Rugby Union Weekly: Another huge weekend in the Six Nations is unpacked by the boys
- 1 Xtra's Money Moves: Top tips on a positive approach to managing your finances