Mercedes have downplayed suggestions that they are the early favourites but are "cautiously satisfied" after the first pre-season test.
While reigning World Champ's Red Bull Racing struggled to string a handful of laps together at Jerez, Mercedes were quickly into the action.
Putting in 309 laps compared to Ferrari's 251, McLaren's 245 and Red Bull's 21, the Brackley squad had the better of the running.
That, together with the fact that the team designs not only the car but also the engine, has led to claims that they could be the team to beat.
Toto Wolff, however, has downplayed.
"I think these people should look at the past," the Merc executive director told Autosport.
"Very often the so-called favourites after the first couple of days of testing were not the favourites when the season actually started or panned out. It is too early right now."
He did, however, admit that Mercedes were "cautiously optimistic" after the first four days of running.
"I would say we are cautiously satisfied. We thought that we could be running into more problems than we actually did with the whole new concept.
"It looked difficult on the first day of testing, but in the end the car seems to be running reliably.
"We cannot judge performance yet - we are far away from performance, far away from what we think what our potential is.
"There are still little bits and pieces missing, and not functioning in the way we want them to function.
"But we are cautiously optimistic and it looks like the guys have done a good job."
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