The 14th-seeded Sharapova, who won the Australian Open in 2008 but missed last year's tournament because of shoulder surgery, fell behind 4-1 in the third set. Sharapova rallied to get back to 4-5, but had her serve broken in the final game.
Novak Djokovic wonders if the old order on the men's side is about to be shaken.
Yes, Roger Federer and Rafael Nadal seem to have a monopoly on Grand Slam tournaments, having won 17 of the last 19 majors between them. But with the Australian Open ready to go, Djokovic suspects change at the top may be coming.
"I think it's getting very interesting, men's tennis," he said. "It's good for the sport to have a good group of the players that are able to win."
Djokovic upset Federer in the Australian Open semifinals two years ago en route to the title. Djokovic, ranked No. 3, said Juan Martin del Potro's win over Federer in the U.S. Open in September has given players a confidence boost.
No. 4 del Potro, No. 5 Andy Murray and No. 7 Andy Roddick all play today, when the bottom halves of the men's and women's draws get started. Del Potro withdrew from an exhibition tournament at Kooyong last week because of an injured wrist, but his agent said he's expected to be fine for the Australian Open.
Roddick warmed up with a title run at the recent Brisbane International.
Kim Clijsters was the second match on center court, facing Valerie Tetreault of Canada. Clijsters won the U.S. Open in September in only her third tournament back from time off after getting married and having a baby.