Sir Jackie Stewart has tipped fellow multiple world champion Michael Schumacher to keep racing beyond 2012.
"He has had a lot of criticism," the triple world champion told Kolner Express newspaper, "including from me."
Triple world champion Stewart, 72, said the famous German has taken a lot of time to get back up to speed since returning in 2010, but the final piece of the puzzle is a strong Mercedes in 2012.
"He has had a hard time. So why should he stop now that he knows he can still keep up with the boys?
"I think he wants to collect the fruits of the work that he has been doing with Mercedes," the Scot added.