Former Mercedes chief Norbert Haug doubts that the German manufacturer's rivals have been able to track down the its advantage ahead of the 2015 Formula One season.
At the opening pre-season test at Jerez last week, it was Ferrari who surprisingly set the headline times with its new SF15-T
But Haug, the former head of Mercedes motor sport, said: "There are no points for testing.
"If there was, we would have seen a completely different game," he was quoted by Germany's Sky.
"I think Ferrari has taken a step, but I believe that the gap Mercedes had (in 2014) means they are clearly once again the favourite."