- First Barcelona Test - Day Two
Ferrari pace an eye opener - Rosberg
Mercedes is wary of its rivals' progress over the winter, with Nico Rosberg especially concerned about the pace of the Ferrari during winter testing.
Mercedes has been focusing on long runs during the six days of testing so far, but have been outpaced by Ferrari in every session. Although lap times in testing can be notoriously misleading, Rosberg said Mercedes has genuine cause for concern.
"It's clear in the way that the others have really stepped up their game, so the other's [pace] is surprising to us," he said. "In relation, it seems that Ferrari has made the biggest step to us.
"Definitely our eyes are wide open at the moment."
Asked if he was happy with Mercedes' improvements since the Jerez test, Rosberg said: "You can never be happy but I am confident we will get things done the way we want. Things are improving, yes."
Rosberg only completed a half day of 66 laps on Friday due to a neck strain which developed during testing in Jerez.
"I'm just being careful," he explained. "I know the cause of it, which is my position in the car which I got a bit wrong [in Jerez] and didn't realise. But I'm just being careful, it's all fine. I can't drive the position I like because my neck doesn't like that one. It's incredible what a fine line it can be, just a couple of millimetres - centimetres in this case - but it changes everything.
"It was just the position of the spine. We have such g-forces that you have to make sure everything is in line and make sure all the forces are right, and it was not quite right. I have to get used to it again, it doesn't take long, but it's different."