Felipe Nasr says that he needs to improve the feel of the brakes on his Sauber C34 if he is to be competitive at this weekend's Austrian Grand Prix.
Having claimed ninth in Monaco, Nasr slumped to 16th in Canada as he struggled with the revised braking material used by the Swiss team.
Nasr says that his priority during Friday's practice session in Austria is to re-find his feel with the brakes, or else he will revert back to an old set-up.
"I’ve been running with another material since the beginning of the year but the last two rounds we were with another supplier, for Monaco and Canada, and this is where I’m finding it difficult," explained the Brazilian rookie.
"I was so used to the other material and because Canada and here is such high on the brakes, that’s why we had to change the material, but it hasn’t suited my driving at all.
"We made some modifications to the brakes here and I’ll be trying them on Friday, if not then we have another solution to try.
"If I cannot stop the car properly on the beginning of the car then you compromise all the rest of the corner – this was the case in Canada and I was compromising my exits, I was never happy there."