Although most expect Mercedes will have the upper hand in Melbourne, Toto Wolff says they could face competition from Ferrari and Williams.
Last season Mercedes romped away with the Championship double as Lewis Hamilton and Nico Rosberg claimed 16 of the 19 grand prix wins.
It was a phenomenal performance from Mercedes who enter this year's Championship as the team to beat.
Rosberg and Hamilton finished first and second respectively in the final pre-season test at Barcelona, although the likes of Williams and Ferrari were not too far behind.
Mercedes, though, had a few reliability issues over the course of testing which could open the door for their rivals to attack.
"I wouldn't really try to read too much into lap times, because we don't know what fuel loads people were running," Wolff, Mercedes' motorsport boss, told Autosport.
"We would be trying to read a crystal ball and that's not what we should do and not what I would like to do.
"Although we have been running solid and the pace is good and the long runs are good, reliability is still an issue.
"It's always going to be an issue for everybody and we need to get on top of that and then just wait and see how the first couple of races pan out. Then it's probably easier to confirm what we've seen in testing.
"Ferrari has been looking good, Williams has been looking good, so let's wait until the racing really starts."