Serena Williams’ coach Patrick Mouratoglou believes the tennis legend will not quit until she at least equals Margaret Court’s record of winning 24 Grand Slam singles titles.
The American former world number one is one short of reaching that landmark, having missed out during her latest attempt by losing to eventual champion Naomi Osaka in the Australian Open semi-finals.
The 39-year-old had looked in good form up until that point, but left her final press conference in tears after she was asked about her future in the sport. She said if she was going to retire, she would not be telling anybody in advance.
Murray, Djokovic in, Williams, Federer out - who's playing tennis in Tokyo?
- Done? Signs suggest Serena's quest for No.24 is almost over, but hope remains
- It's not the end for Serena - Wilander's view after Osaka win
- 'Huge goodbye' - Is this Serena's final farewell moment?
But Mouratoglou believes Williams, who returned to the sport after giving birth to her daughter Alexis Olympia in 2017, was caught up in the moment.
"It's something that is difficult to measure for people," he told People.
"That's why it's very sensitive. That's why it's very emotional for her. I completely get it.
I don't think she will stop until she at least wins a Grand Slam, because she came back to win Grand Slams. She doesn’t quit.
'I'm honoured to play when she does, to experience her greatness' - Djokovic on Serena
Mouratoglou thinks Williams is motivated to add to her collection of major titles, with three more opportunities to do so in 2021 alone.
"I have to believe it and she has to believe it, too. If she [doesn't], she would stop”, he said.
“After all she's achieved in her career, at her age, having a baby for the first time, having a family - it was an incredible effort to come back to tennis, unbelievable effort.
Mental effort, physical effort, so many hours to get back in shape. She would never even start that if she didn't think she was able to win a Grand Slam.
"That's how Serena is really exceptional. She puts the standards so high for herself, and she finds a way to match those standards, whatever she does."
'Huge goodbye' - Is this Serena's final farewell moment?
On the constant questions about when Williams will choose to hang up her racket, Mouratoglou says it will not be a decision she takes lightly, when she finally decides to do so.
“I don't think she planned [retirement] for this certain moment. She's dedicated all her life to tennis since she was a kid," he said.
"So the day she will retire, she will feel like she's giving an end to 40 years of a life."
'Federer not among Wimbledon favourites, Djokovic super favourite' - Mouratoglou
Wimbledon LIVE - Murray in action after Djokovic and Sabalenka win through