Vettel's real test will come when he does not have the best car says Mercedes GP boss Ross Brawn.

Ross Brawn: For Sebastian, what will come now, which will be an interesting phase of his career, will be when he has not got the best car," explained Brawn, who famously helped Michael Schumacher turn around Ferrari after he joined the team following back-to-back titles for Benetton. I think you have a fantastic driver in the best car, and that combination is unbeatable. It will be interesting to see Sebastian's role, Sebastian's influence, Sebastian's position when perhaps he does not have the best car, he has to make it the best car, and has to create the best car. That will be another chapter of Sebastian Vettel when it comes - and it will come.