/> While Naseeruddin Shah is yet to work with his elder son Imaad, the stalwart's younger son Vivan has lucked out twice over. After acting together in Vishal Bharadwaj's Saat Khoon Maaf, Naseer and Vivan are back together, this time as two gangsters who split and go their separate ways in a film entitled Mastaan.

While Vivan plays the young Haji Mastaan, Naseer will play another reputed gangster of the era Karim Lala.

Interestingly Naseer and Vivaan shared no screen space whereas this time in Mastaan they've extremely critical dramatic scenes together.

Says a source very close to the project, "It was a major concern for Naseer. He didn't want to put Vivaan under the pressure of having to perform with his dad so early in his career.

During Saat Khoon Maaf Naseer wouldn't be around on location when Vivaan was facing the camera. Naseer initially hesitated about doing Mastaan. But then the two roles are so powerfully written that Naseer is confident his boy would stand up to his father quite well. "

Vivaan has begun preparation for his role as Haji Mastaan reading up on the era and on the gangsters who occupied that era.

However Vivaan has been asked not to watch Amitabh Bachchan in Deewaar and Ajay Devgn in Once Upon A Time In Mumbai. The two actors have played roles allegedly inspired by Haji Mastan. But the director doesn't want Vivaan to bring any baggage into his part.

The film to go on the floors in May, will be directed by first-timer Rocky Khanna.

Says the excited producer Sunil Bohra, "The only thing I knew about Rocky Khanna is that he had written the lyrics of a film called Main Meri Patni Aur Woh. I had no clue he could write a script or direct a film. But when I heard the script of Mastaan I was blown. There have been many films about the underworld and gangsters and about Haji Mastaan. But this one is something else. "

Bohra says it had to be Naseer for the older part and Vivaan for the younger role.

"Rocky was clear on that. If we didn't get Naseer Saab and his son we wouldn't make the film. Luckily they both agreed. "

The 20-crore rupee budgeted film will be set in the 1980s.

Interestingly the film also marks a new beginning for singer Mohit Chouhan of Rockstar fame. He turns music composer with Mastaan. No singer had concerted ti composition so early in his career.