Serena Williams has abruptly finished an Australian Open media conference in tears amid questions about whether this was her final appearance at Melbourne Park.

Williams appreciated the warm applause of the Rod Laver Arena crowd

Williams was facing the media less than an hour after leaving the court on Rod Laver Arena following her 6-3, 6-4 semi-final defeat to Naomi Osaka on Thursday afternoon.

She answered a question about whether she may have been saying farewell to the crowd when she had her left hand on her chest as she waved to spectators while exiting the court, before being asked about the number of unforced errors she made during the match.

Williams began to answer but had to stop when she was overcome with emotion.

"I don't know. I'm done," a tearful Williams said before standing up to leave the media conference.

There was speculation her gesture to the Rod Laver Arena crowd signalled this could be her final Australian Open.

When asked about this earlier at her media conference, Williams replied: "I don't know. If I ever say farewell, I wouldn't tell anyone."

The 39-year-old said she was touched by the applause of the crowd.

"The Aussie crowd is so amazing, so it was nice to see," she said.

Williams later took to Instagram to thank her supporters in Australia.

"I am so honored to be able to play in front of you all," Williams 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 everyone single one of you.

Congratulations on a great fortnight, @serenawilliams.

We can't wait to see you back here next year 💕#AusOpen | #AO2021 pic.twitter.com/ccugVe6lcj

— #AusOpen (@AustralianOpen) February 18, 2021

"I love you. I love you. I love you. I adore you."

The loss to Osaka ended Williams's bid to win a record-equalling 24th major singles championship at this year's Australian Open.

Williams was scathing of the number of errors she made in her defeat to Osaka

Her 23 titles leaves her second only to Australia's Margaret Court.

Williams first entered the Australian Open women's draw in 1998 as a 16-year-old.

She has contested 20 Australian Opens, winning seven singles championships and four doubles crowns.

Williams said she made too many unforced errors in the defeat to Osaka.

"I felt like I was hitting well," Williams told her media conference.

"I was hitting well this whole tournament. Even the first couple games I played well. Even then I had so many opportunities … just made too many mistakes there, easy mistakes.

"Not like I was on the run or anything, they were just easy, easy mistakes."

Osaka will play Jennifer Brady in Saturday night's final.