Nico Rosberg piloted the Mercedes W06 today, only out-paced by Ferrari power.
Nico Rosberg says Ferrari's form in testing at Jerez has been an 'eye-opener' to his Mercedes Formula One team.
The Maranello squad set the pace on the opening two days of work in Spain thanks to Sebastian Vettel, and teammate Kimi Raikkonen finished in second place in today's session.
Here the goal is to do mileage because last year it was our weakness, so we have a big focus on that
The Finn, however, was only outpaced by the Sauber of Felipe Nasr, who used the softer Pirelli tyres to finish on top of the times.
Ferrari pace a surprise
While Rosberg says he is comfortable with Mercedes' form, the German suggested Ferrari's pace has been a surprise.
"The general feeling is we've come a long way as a team, we are a strong team," said Rosberg. "We are keeping an eye on the opposition and especially Ferrari has been an eye-opener for us in the last couple of days.
"Still, we are confident that we can start the season well and also be strong in terms of development."
Reliability vs. performance
Rosberg admitted Mercedes was not focusing on extracting performance from the car at Jerez, but rather on making sure the team avoid the reliability issues it had last season.
"Here the goal is to do mileage because last year it was our weakness, so we have a big focus on that, to have a really reliably car this year because it costs us some points last year. So that's been the goal to start off, because it's important to see the problems now before Melbourne," Rosberg added.
"The problems that you see in Barcelona is going to be short [on time] so it's more difficult to solve them. So everything that you can find here is easier to solve.
"We did find some weaknesses on the car already but they are going to be easy to fix, so we are on the right track."
Rosberg managed a mammoth 151 laps today, but stopped on track once due to a problem with his car's telemetry.