Mark Ruffalo has revealed that Robert Downey Jr played a huge part in him taking on the role of the Hulk.

Mark Ruffalo

Mark Ruffalo

Ruffalo played Bruce Banner for the first time back in Avengers Assemble in 2012 and has reprised the role in Avengers: Age of Ultron over the weekend.

The Oscar nominated actor admits that he did have fears about taking on this role and stepping into the Marvel world, but Downey Jr helped him make that leap.

Speaking to People magazine, the actor said: "He's kind of my godfather in the world. He sort of gave me the okay to come join and has sort of bolstered me along the way when I've had my doubts, which are plenty. And he has made sure that (Bruce) Banner's been well represented."

Age of Ultron sees Ruffalo share more screen time with Downey Jr as well as a terrific Hulk vs Iron Man fight in the middle of the movie. And Ruffalo says that he had the Iron Man actor have a great working relationship.

He continued: "He's been just a bro to me. He also, he thinks I'm a little insane. So when we get into those moments (during filming), we are half laughing through the whole thing. He's half like, 'Ruffalo, how do you even get up out of bed?'

"He has the most endearing sort of patience and tolerance for me. And we literally are laughing behind everything. I don't know what's going to come up with him, which makes it so much fun and alive."

Age of Ultron has already stormed to the top of the UK box office - taking £18 million in the process - and over £200 million worldwide. The film is set to be released in the U.S. tomorrow, where it will be a monster commercial hit.

Sadly, a solo Hulk movie is not currently in the pipeline and there has been no announcement as to where we will see this character appear next. As for Iron Man, he is set to join the Captain America franchise for the first time as filming on Civil War is about to get underway.

Ruffalo is currently filming Now You See Me: The Second Act - where he will reprise the role of Dylan Rhodes - and he has already completed work on Spotlight.

Avengers: Age of Ultron is out now.