Williams senior engineer Rod Nelson has admitted that he is 'surprised' at how quickly Felipe Massa has adapted to his team after leaving Ferrari at the end of last season.
The Brazilian left Ferrari after eight seasons at the Maranello team at the end of 2013 having previously spent three years at Sauber.
"Felipe's good, make no mistake," Nelson told Crash.net.
"He's the real deal. He's got a lot of experience. I know Fernando [Alonso] very well obviously because I was at Renault for four years and Felipe is no slouch.
"He's open enough to do things that maybe he's not as convinced about. He's quite open minded about things and you know what his opinion is when you speak to him. All you're after is honesty. I think he's surprised us, actually."
Nelson added that Massa's 11 years' experience as a Formula One driver has been very beneficial to Williams during an off-season that is arguably more important than previous years.
"You need solid homework. On the engineering side you need guys that are on it and you also need a driver that is not going to get too excitable and is going to be happy doing the homework for you and he fulfills that role," Nelson added.
"He's good. You could put a young guy in the car but if you did that you pay your tax, and he's been there before."