Directed by debutante Sudha Kongara Prasad, the sports -drama features Madhavan as a hard task-master boxing coach and also stars boxer Ritika Singh.
"The most difficult task for me was to find a girl who looks like a 17-year-old and is also a boxer and actor. All these things put together looked like an impossible task," Madhavan told reporters here this evening.
The actor was speaking at the trailer launch of the film, co-produced by him and filmmaker Rajkumar Hirani.
The 'Tanu Weds Manu' actor said he did not have to work hard on Ritika's boxing skills as she already knew the moves perfectly.
"It was easy because we didn't have to tell anything to her regarding boxing. After every scene we used to say nice performance, nice expression but she was concerned if her punches were good."
'Saala Khadoos' weaves a story around how a coach prepares a young girl to create a place for herself in the world of boxing. It is slated to release on January 29. Hirani said while everyone was excited about the idea of having a real boxer play the role, he was a little apprehensive.
"The thought came from Sudha and Maddy (Madhavan) that we should cast a boxer. Because the film has a lot of boxing matches and if a boxer plays the role it will look real. I was the one who was averse to the idea because we will get a boxer but how will she act."
"She (Ritika) is very real. She is not trying to act there is a roughness in her voice and because being a sportsperson there is some amount of focus she has. So we took a chance," the "3 Idiots" director added.
Madhavan is aware of the inevitable comparisons that will be made with the film to other sports-based movies like 'Chak De India' and 'Mary Kom'.
"From 'Mary Kom' to 'Chak De India' to 'Paan Singh Tomar', comparisons will be made because all these films have been very successful. Its good if our film is also compared with these successful films," the 45-year-old actor said.
Hirani said there will be certain similarities owing to the film's sports theme.
"This is a sports film so there would be a coach, similarities... But there are various ways of saying the same story... What inspired me was the unique story but we work so slow that something always comes first. When we were making 'pk', 'Oh My God'. came when we started making this, 'Mary Kom' came. So we really can't help that."
