After back-to-back 6-0, 6-0 wins in the first two rounds, Sharapova has conceded the fewest number of games en route to the fourth round.
Still, she knows she must stay on top of her game because the younger of the Williams sisters could be waiting. Since Sharapova won the French Open, to complete a career Grand Slam of all four major titles, Serena Williams has won just about everything.
Asked whether she was thinking about a showdown with Serena Williams, Sharapova said: "She's on the other side of the draw, and other players are on the other side of the draw as well."
That means they can meet only in the final.
The top two contenders on the opposite side of the draw, defending champion Victoria Azarenka and Serena Williams, play one after the other at Rod Laver Arena on Saturday. Top-ranked Azarenka is first up against American Jamie Hampton, followed by Williams against Ayumi Morita of Japan.
U.S. Open champion Andy Murray follows them in a third-round match against Ricardas Berankis, a qualifier from Lithuania. Four-time Australian Open champion Roger Federer has the night match against Bernard Tomic, the last Aussie in the men's or women's draws.
Top-ranked Novak Djokovic took another step closer to a third consecutive Australian title, defeating Radek Stepanek, 6-4, 6-3, 7-5, in the third round.
His victory came after Lance Armstrong admitted during a TV interview with Oprah Winfrey that he used banned drugs to win his seven Tour de France titles. Djokovic, a lifetime cycling fan, said at his post-match news conference that it was "a disgrace for the sport to have an athlete like this."
"He cheated the sport," Djokovic said. "He cheated many people around the world with his career, with his life story."
Djokovic will play Sunday against No. 15 Stanislas Wawrinka, who knocked out the last American man in the draw with a 7-6 (6), 7-5, 6-4 win over No. 20 Sam Querrey. For the second straight year, there will be no American men in the fourth round at Melbourne Park.
In the last match of the day, fourth-seeded David Ferrer finished off a 6-4, 6-2, 6-3 win over 2006 Australian finalist Marcos Baghdatis with an ace, advancing to a fourth-round match against Japan's Kei Nishikori.