Serena Williams ended her press conference in tears after talking about saying farewell post her heartbreaking semi-final loss to Naomi Osaka at the Australian Open on Thursday.

The 39-year-old fought hard to hold back tears and walked out of the press room saying “I’m done”.

On court, the Japanese third seed swept past the American veteran 6-3, 6-4. The loss left Williams, who won her last Major in Melbourne in 2017 while pregnant, stranded on 23 Grand Slam titles as she strives to match Margaret Court’s all-time record. She has since lost four Grand Slam finals and a semi-final.

Read: What Serena’s tears after Australian Open exit tell us

Williams, 39, broke early for a 2-0 lead before Osaka reeled off five straight games to leave her shellshocked.

“The difference today was errors. I made so many errors,” said the 23-time Grand Slam champion. “Honestly, it was opportunities where I could have won. I could have been up 5-0. It was a big error day for me.”

When asked whether her gesture of holding her hand over heart on the way out was a message, Williams said: “I don’t know. If I ever say farewell, I wouldn’t tell anyone.”

On the next question about unforced errors, she broke down and left.

Watch: After win over Serena Williams, the Naomi Osaka gesture that won hearts

Williams then posted a long message on her Instagram thanking fans for the support.

“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 said. “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. I love you. I love you. I love you. I adore you.”

Osaka, who is 16 years younger than Williams and grew up watching her, said she was honoured to be on the same court.

“I mean, it definitely means a lot. I think, of course, every time I play her, I feel like it’s something I’ll definitely remember a lot,” she said, adding that talk of the American retiring made her “sad”.

“I want her to play forever,” she said. “That’s the little kid in me.”

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