Steve Coogan and John C. Reilly were "co-dependent" while shooting 'Stan and Ollie'.
The two actors portray comedy legends Stan Laurel and Oliver Hardy in the new movie and they quickly developed a close bond from working together, with the 'Alan Partridge' star praising his new pal for his work ethic and sense of fun.
He said: "I got to know him because we were working closely and we were co-dependent. It was a partnership. We were a team, and we had Jon S. Baird guiding us.
"John and me inevitably became friendly and close.
"What I learned from watching him is that he's fastidious about his job. John is all about the work, with no star BS behaviour. He's always about making it authentic and real.
"He would call things out sometimes, when they weren't quite believable. A couple of scenes were re-shot because they didn't quite ring true.
"He's committed, very professional, and also good fun. We made each other laugh. It was an utter delight."
The 53-year-old actor didn't think the movie would have worked so well if he hadn't forged a friendship with John.
He told Collider: "I wanted to make sure that John and I were well-matched in what we were doing, and that we built up a trust and a friendship to help us with the roles...
"When you've got a good partner, then you've got a job halved."
Steve also admitted he felt "anxious" about not doing "justice" to the real Stan.
He said: "I could do an impersonation of him, but I didn't want the role to be a superficial facsimile of who Stan was. I wanted to do him justice. ... I was anxious about it not having depth.
"Impersonating someone is quite useful sometimes, but it can be fraught with danger and only skin deep. I was anxious about that, and wanted to make sure that wasn't the case.
"The other thing was the physicality, but I knew that if I put the work in, I could get that right. There's a great clown advisor, called Toby Sedgwick, who taught us tips on how to move, gestures, physicality, and dancing. Once we were off to the races, we knuckled down and I thought it was doable, especially with John."
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