Melbourne - Serena Williams begins her quest Monday to equal Steffi Graf's Open-era record of 22 Grand Slam titles battling fitness concerns and with a host of players desperate to dethrone the defending champion.
Following a dominant 2015, the world number one is gunning for a seventh Australian crown adamant that she is over the knee problems that hindered her during the latter half of the year and during her Melbourne Park build-up.
She insisted on Saturday she was "120, 130 percent right" as she prepares for a tricky first-round encounter with Italian Camila Giorgi, the highest ranked non-seeded player in the women's draw.
"I've had a really good preparation. I mean, I didn't have the match play that I've wanted to have," said the 34-year-old American.
"But after playing for so many years on tour, I should be able to, you know, focus on that and the fact that I have played a lot of matches. So that's what I'm trying to focus on now."
Her three Grand Slam titles last year in Australia and at Roland Garros and Wimbledon took her within one of Graf's long-time record of 22 and put her three clear of both Chris Evert and Martina Navratilova.
Melbourne Park has been a happy hunting ground. She claimed her first Australian Open title way back in 2003, beating elder sister Venus in the final, and reached her sixth last year when she toppled arch-rival Maria Sharapova.
Williams is in a tough half of the draw with Russia's Sharapova, seeded five, potentially awaiting her in the quarters.