Nico Rosberg admits Mercedes does not know if Ferrari is ahead or behind in the pecking order ahead of the Australian Grand Prix.
Mercedes did not run on either of Pirelli's softest compound tyres throughout testing and only opted for a small amount of laps on soft tyres throughout the eight days. On Thursday Kimi Raikkonen set the fastest time of winter testing and also went 0.013s quicker than Rosberg on the soft tyre, though it is often difficult to draw accurate conclusions from individual lap times during the winter.
Some in the paddock have said that Mercedes' long run pace suggests another season of dominance is on the cards but Rosberg is yet to be convinced.
"They have been very quick for sure," Rosberg said of Ferrari. "All the teams have their strategists so we know more or less what fuel the other teams are running and they know our fuel.
"So we know more or less where we are compared to Ferrari - which is why I say for sure it is close. But we are not sure if we are ahead or behind."
When asked what he would say to those saying Mercedes is in a different league, he replied: "I just say let's wait two weeks ... I hope they are right."
Rosberg also thinks the timing of winter testing and the characteristics of the Circuit de Catalunya justified Mercedes' decision to only run on medium and soft tyres.
"Well there is a potential small downside but at the same time is it really representative? Because here you have 20 degrees which is completely unrepresentative, the track is not a track where you are going to be running those soft tyres because this track is not made for that so it's limited. I'm sure they really thought about the tyre choice they made for testing and this was the way to go."