Melbourne: Seven times world champion and four times winner of the Australian Grand Prix, Michael Schumacher refused to get too excited about finishing top of the timesheets in a practice session on Friday.

The German has not been on the podium since he began his comeback to Formula One after three years in retirement in 2010 and the third-fastest time of the day overall was a small glimmer of hope that 2012 might offer better things.

"Today was a nice start into a hopefully exciting season, and certainly two promising sessions for us," the 43-year-old said.

"However, I would not go so far as to speak about being confident as the weather conditions were too mixed to gain a clear picture."

The first two practice sessions of a race weekend are often a poor gauge of the relative pace of cars because teams try out different set-ups before the important business of qualifying on Saturday.

The most successful driver of all time, Schumacher is preparing for his 288th race at the start of his 18th full season in Formula One and was under no illusions on Friday.

"We know what Friday sessions are for and don't know what fuel loads others were running," Schumacher added.

"On the other hand, it is good to see that we were competitive in different circumstances today and that the car provides good handling - I just feel it."

Two positive pre-season tests in Barcelona indicated that Schumacher and his Mercedes team mate Nico Rosberg might be contenders this year.

Team boss Ross Brawn on Friday reflected Schumacher's caution but also his guarded optimism.

"It's certainly better than being at the back," he said. "It's been a reasonably encouraging start but we're not getting carried away. Different teams were doing different things today."

Last season, Schumacher and Rosberg both retired at Albert Park on their way to finishing eighth and seventh respectively in the drivers' standings.

Brawn said the team had arrived in much better shape for the season-opener this year.

"We're much better prepared than we were last year," he said. "Last year we were not in good shape at this stage of the season.

"We're not where we want to be yet in many ways but we're a lot better than we were 12 months ago. If we keep that rate of progress going then I'm extremely optimistic about the future.

"We're at a place now where the car...does all the basic things properly and all of our resource can be focused on trying to find performance for the next part of the season."