Felipe Massa is "the real deal" and has "surprised" Williams with his approach, according to senior engineer Rod Nelson.

Kimi Raikkonen's return to Ferrari saw Massa replaced at the end of 2013, and he moved across to Williams to partner Valtteri Bottas. Having driven in F1 for 11 seasons - eight of which were for Ferrari and three for Sauber - Massa is only at his third team and chief test and support engineer Nelson said working with him so far as been impressive.

"Felipe's good, make no mistake," Nelson said. "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 explained that Massa's experience was also proving beneficial in a season where testing takes on even more importance than in 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 fulfils that role. 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."