World number one Serena Williams, beat rival Maria Sharapova for the 18th straight time to make the last four, made her professional debut in 1995 and few players from that era remain on tour, aside from sister Venus.
The Melbourne Park top seed, who next faces Agnieszka Radwanska, is proud to still be playing and at the top of her game.
“I think longevity is something definitely to look at. Personally, I didn’t think I’d be playing at this age,” she said as she guns for a seventh Australian Open crown.
“But I’m still here and I’m doing well. I think that’s the reason I am still playing, because I know that I’m capable, you know, if I play well, of being on top.”
Despite remaining an invincible force, the driven American said she had learned to relax and was enjoying her tennis greatly now that the clock was ticking on her career.
“I think this tournament in particular I’ve been trying to do different things and I’ve been having a lot of fun on the court,” she said.
“I told myself that I’m here to have fun now. I’ve done everything… I didn’t think I would have done as well as I have.
“Everything from here on out, every match, is a bonus for me. I don’t have to win this tournament or any other tournament for as long as I live.
“I really want to enjoy being a professional tennis player and playing on Grand Slam courts, moments like this.”
Asked what the secret was to her longevity, she replied: “I honestly have no idea. If I do know it, I’ll probably put it in a bottle and distribute it.”