Billie Jean King has hailed Serena Williams as the greatest female tennis player of all time following her Wimbledon triumph over Angelique Kerber on Saturday.
The American equalled Steffi Graf's Open Era record of 22 Grand Slam titles with a 7-5 6-3 victory over the German, claiming her seventh title at SW19 in the process.
Williams is now just two titles short of Margaret Court's all-time record of 24, and King challenged her to surpass that total and prove unequivocally that she is the best female to have played the game.
"Didn't Stefanie Graf win seven? And she also holds 22 so she's right in line with Stefanie. Margaret's got 24. So if she can keep her motivation and stay healthy maybe she'll be our greatest ever," she told BBC Sport.
"I think she should be, I think she is, but she still has to prove it. I think she should go on to win more. I always talk about how the head, the heart and the guts have to be together to make greatness and that's what Serena has.
"You can find lots of terrific physical athletes - you can find tons - but if they don't have it emotionally and mentally they're not going to make it. She hates losing and I love that fact: that's what makes her so great."
Williams has also won the Australian Open and US Open six times, as well as picking up three French Open titles.