"Well, let’s just say he is a world champion," he said during the interview.
Speaking to the Hindustan Times, the 86-year-old compared the retiring champion to contemporaries Lewis Hamilton, Sebastian Vettel, and Fernando Alonso - all of which he says achieved more during their time in F1
"The other names that you mentioned (Hamilton, Vettel, Alonso) have obviously won more than a few times and have achieved more," he said. "So I would just call Nico a world champion and nothing else."
However,he did admit that Rosberg will be missed in future Formula One seasons.
"Okay, not as popular as Lewis but Nico was a very popular driver. So his absence is certainly not good for Formula One," he said.
Bahrain International Circuit - Winter testing