Williams got a strong start to the new season, with back-to-back wins over Sharapova and Azarenka earlier this month in Brisbane. She beat Sharapova in the semifinals and overcame Azarenka in the final.
In Melbourne, Williams will only get the chance to play one of them. Azarenka and Sharapova are on the opposite side of the draw from Williams and could end up playing each other in the semifinals.
Sharapova's first-round match is against Bethanie Mattek-Sands on Tuesday, when Azarenka faces Johanna Larsson of Sweden.
Williams has 2011 U.S. Open champion Sam Stosur and two-time Australian finalist Li Na in her half of the draw.
She starts her Australian Open campaign Monday against 153rd-ranked Australian teenager Ashleigh Barty, who was trying to look on the bright side about the match.
"I'm just going to go out there and enjoy it," said Barty, who is 17 and ranked 153rd. "Not every day do you get the opportunity to play the No. 1 player in the world and one of the greatest champions of all time. I'm really excited for the challenge."
Barty is bound to have rowdy home crowd support as she steps onto center court against the world's top player.
"Obviously they'll want Ashleigh to win, (and want) her to do well," Williams said. "Under any other circumstances. I'd probably be rooting for her as well."
