"This is the first time I've really had to make adjustments in my game," said Sharapova, referring to her injury layoff. "After coming back from a long period, you have to adjust to the speed, reaction time, stuff that usually comes natural to you."
Sharapova won her first tournament as a professional at the Japan Open in 2003 and won in Tokyo in 2005. With more seeded players losing Tuesday, including third-seeded Elena Dementieva, she is positioned well for another shot at a title.
"The more rounds you play, the tougher it gets," Sharapova said. "You've got to take it one match at a time and not think too far down the road."
Dementieva became the latest highly ranked player to lose in the second round, falling to Ukrainian qualifier Kateryna Bondarenko 6-2, 6-7 (3), 6-1.
Fourth-seeded Caroline Wozniacki of Denmark, trailing 5-0, was forced to retire with a viral infection in the first set of her match against Aleksandra Wozniak of Canada, and fifth-seeded Svetlana Kuznetsova also lost Monday.
"I don't know about the other players, but I feel like I didn't have enough time to recover after the U.S. Open," Dementieva said. "It's hard to get ready for such a big event like this and I just wish we had more time."