Nico Rosberg has admitted that is struggling to get the best out of Mercedes GP's major update package for this weekend's Spanish Grand Prix.
The German, who has comfortably outperformed seven-time champion Michael Schumacher so far this season, could only manage eighth on the grid as his more experienced teammate outqualified him for the first time this year. While Schumacher has expressed his satisfaction with the updated Mercedes MGP W01, Rosberg is working to understand the problems he is having with the car.
"It's been a difficult weekend for me and we need to look into the reasons for this and understand why," said Rosberg, who is currently second in the drivers' championship behind Jenson Button. "The changes that we have made with the car are obviously good and we have made a step forward but I haven't really been able to use the improvements so far.
"Considering that I have found the car difficult to drive and haven't had the best of setups, our performance today was acceptable – but it's not where I wanted to be fighting this weekend."
Team boss Ross Brawn believes that the changes made to the car for this weekend have provided a step forward in performance, despite Rosberg's struggles.
"I'm not happy with the overall performance, but I am confident that if we hadn't done all of the work that we have, we would have been much further back," said Brawn. "Michael has continued the progress that we saw in the first three races while Nico hasn't been completely happy with the car this weekend and that reflects in his position. I am comfortable that we have made progress but other teams have also moved forward so we have further work to do."
Schumacher will line up two places ahead of Rosberg in sixth, and he believes that getting higher up the grid was not possible.
"I feel a lot more comfortable driving the car that I have in my hands now," said the 41-year-old. "But there is a maximum that you can get out of it, and that is what we achieved today."