The French Open champion pulled out of the Brisbane tournament on Tuesday after feeling pain while practicing before her opening match.
"I still have quite a bit of time to prepare for Australia. I'm on the right track, been training really well, so I just don't want to jeopardize what I've gained in the offseason so far," the No. 2-ranked Sharapova said. "Just have to make a smart move here."
The 25-year-old Russian also withdrew from the Brisbane International last year because of injury but recovered quickly to reach the Australian Open final, where she lost in straight sets to Victoria Azarenka.
She said the latest injury also forced her to withdraw from a recent exhibition tournament in South Korea, but was "not at all" related to the right shoulder problem which has plagued her since 2008.
"I had a bit of inflammation in my collarbone, and I sent (scan results) to a doctor in New York and he told me I couldn't really do much overhead training for about a week," she said. "So to be fair, I haven't really given myself a chance to pretty much hit any serves or anything over my head ... So I just kind of ran out of time here."
Sharapova said she'd started practicing her serves again on Monday and it wasn't enough time to properly prepare for a tournament featuring eight of the top 10 women. The Australian Open starts Jan. 14 at Melbourne Park.
The four-time major winner told a news conference earlier in the Brisbane tournament that she felt relaxed and relieved to have finally broken a Grand Slam drought by winning the French Open last year. The win at Roland Garros completed a career Grand Slam and was her first major title since the 2008 Australian Open.
On Tuesday, she reiterated she was "feeling so much better."
"I just don't want to jeopardize what I've built on," she said, adding that her decision to skip the 2012 Brisbane tournament was a good example of putting her health ahead of match practice. "It's kind of the way that I've always built my career around the fact that it's very important for me to go into something like the Australian Open believing and knowing that I'm healthy, that I'm confident.
"I don't exactly need to play five tournaments in order to feel that way."
Sharapova's absence gives Australia's Jarmila Gajdosova a direct route to the quarterfinals, where she'll meet Slovakian veteran Daniela Hantuchova.