/> Sonam Kapoor has opted out of Mani Ratnam's new Tamil film which launches the veteran Tamil actor Karthik's son Gautham.

Says a source, "At this point in her career going South-wards for Sonam would give the wrong signal to the filmmakers in Bollywood. Mani had his heart set on Sonam since she suited the young innocent effervescent sophisticated girl's role to the hilt. He had to look for a last-minute replacement. "

Interestingly the role has now gone to the rapidly-upcoming Tamil-Telugu actress Samantha Ruth Prabhu who, we have reason to believe, has bagged another role in Tamil that was earmarked for Sonam.

The Tamil-Hindi director Gautham Menon's next Hindi film Assi Nabey Poore Sau had a very interesting role for the female protagonist who had to go from age 15 to 25.

It was finally felt that Sonam would be unable to look 15, no matter how hard she tried.

Samantha who was introduced into cinema by Menon in his Tamil film Vinaaithandi Vaaruvaaya was also supposed to make her Hindi debut in the film's remake Ek Deewana Tha.

He now intends to launch ‘Sam' (as she is widely known in the Tamil film industry) in Hindi cinema in style.

Says a source, "Gautham wanted Samantha for the Hindi version of Vinaaithandi Vaaruvaaya. Having failed in that endeavour, he is now in the process of completing Assi Nabey Poore Sau as a Hindi launch vehicle for her. "

The film pairs Samantha with the Sanjay Leela Bhansali discovery Aditya Roy Kapoor who has disappeared after Guzaarish and Vipul Shah's Action Replay and has been focusing on getting the look and performance as a 15-going-on-25 lover-boy right.

Kapoor has gotten rid of his trademark curly mop of hair and now sports a more sober look.

Says Menon, "Both Sam and Aditya have to have to go through 3 age-transitions from 15 to 20 to 25. Their love story starts when they're 6. Obviously Sam and Aditya couldn't play the 6-year old pair. But the three other stages in the characters' lives have been pulled off effortlessly by the lead air. "

Apparently while playing age-15 Samantha and Aditya Roy Kapoor behaved their characters' age even while not shooting.

The transformation, according to the director, is startling

Come April when Assi Nabey Poore Sau releases Samantha Ruth Prabhu, we hear, will be launched as the next Sridevi in Hindi cinema.

In this she has not only the director Gautham Menon's support, but also the full endorsement of her co-star.

Samantha and Siddharth (UTV) Roy Kapoor and Kunal (Delhi Belly) Roy Kapoor's kid-brother has been spending a lot of time away from Mumbai close to Samantha in shooting.

But that's another story.