MELBOURNE (Reuters) - Serena Williams, with 21 grand slam titles in her trophy cabinet, thinks she has nothing left to prove to anyone and just wants to have fun for the remainder of her career.
The 34-year-old American eased into the semi-finals of the Australian Open with a 6-4 6-1 victory over Maria Sharapova on Tuesday to remain on course for a seventh title at Melbourne Park.
Dismissing the idea that this might be her 16th and final appearance at the year's first grand slam -- "Hopefully not, unless you know something I don't" she said -- Williams spoke of a different approach to her tennis this year.
"I told myself that I'm here to have fun now. I've done everything that I didn't want to do, you know. I didn't think I would have done as well as I have," she told reporters.
"Everything from here on out, every match, is a bonus
"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."
Williams, who played her first grand slam at the 1998 Australian Open, said she had surprised even herself by continuing to play well into her thirties.
"I think longevity is something definitely to look at," she said. "Personally, I didn't think I'd be playing at this age. 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, if I play well, of being on top."
Her grip on the title looks unlikely to be threatened in the semi-finals by world number four Agnieszka Radwanska, who has lost all eight of her matches against the world number one.
"She presents a completely different game, an extremely exciting game," Williams said of the wily Pole.
The only potential cloud on the horizon for Williams at this stage of the tournament is her health.
She came to Melbourne without having completed a set in four months with a question mark over a knee injury and received medical attention twice during her match against Sharapova.
Notoriously cagey about injuries, Williams said it had been nothing more than a bit of treatment for food poisoning.
"Nothing's guaranteed in sport. I still have to win two matches against potentially two extremely tough opponents," she said.
Editing by Martyn Herman