MELBOURNE (Reuters) - Change is as good as a rest, the saying goes, but former world number one Maria Sharapova has had enough of resting and is not about to change for anyone. The Russian spent as much time off the court as she did on it last year as niggling injuries blighted her efforts to rebuild her game after the serious shoulder injury that kept her out for nine months in late 2008 and early 2009. Though she has climbed back as high as 16th in the rankings she failed to make it past the fourth round in any of the four grand slams, prompting some to suggest a radical overhaul of her natural, all-or-nothing attacking game. Sharapova, however, said she knew what works in her game and what does not. "I'm not going to change my game completely to suit certain opponents," the 23-year-old told reporters at Melbourne Park on Saturday. "I know what my strengths are, I know what my weaknesses are and I try to work on the things that need to be improved." Having won three grand slam titles, including victory in Melbourne in 2008, Sharapova knows what it takes to win the sport's biggest prizes. But since returning to the tour in May 2009, she has had to lower her expectations significantly. "I didn't know what I would ever be when I was out of the game for a while and I didn't know if I would ever be back," she admitted. "That was a challenge in itself, just to try to get myself back to playing the sport again. "It certainly took me a lot longer to get back to playing and getting the reactions back. But it's still coming along." Her form may not be as good as she would like but the competitive spirit still burns. "My ambitions are still very much there," she said. "I've been a competitive girl ever since I was pretty much born and I love the sport."