The 47-year-old filmmaker said that Craig knew the role of James Bond inside out and was constantly giving his input into scenes, reported Showbizspy.
"It was pretty feisty. He puts a 100 per cent of himself into it. He doesn't leave anything at home. And he has opinions about everything, which is as it should be," Mendes said.
"But it's very odd because I've never directed an actor in a role which, in a sense, he knows better than I do. Here it's like, 'Well he's played Bond already, so I'm the newcomer'," he added.
Mendes said that his approach to directing the new 007 film was unorthodox and he wanted a small set so he could work closely with his actors.
"Daniel walked on set on the first day, at Pinewood, and went, 'This doesn't feel like a Bond movie.' It was much smaller. I kept it small. I worked hard to keep it on a human scale, for the actors," he said.