Mumbai, Mar 30 (IANS): Sonam Kapoor has opted out of Mani Ratnam's new Tamil film which launches the veteran Tamil actor Karthik's son Gautham. The role has now gone to the upcoming Tamil-Telugu actress Samantha Ruth Prabhu who also will maker her Bollywood debut with "Assi Nabey Poore Sau".

"At this point in her career going Southwards 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," said a source.

The Tamil-Hindi director Gautham Menon's next Hindi film "Assi Nabey Poore Sau" had an interesting role for the female protagonist who had to go from age 15 to 25. Sonam was reportedly considered for the role, but later Samantha was finalised for it.

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

So Menon will now launch her with "Assi Nabey Poore Sau", said 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," added the source.

The film pairs Samantha with Aditya Roy Kapoor, who disappeared after "Guzaarish and "Action Replayy". Currently the actor is focusing on getting the look and performance as a 15-going-on-25 loverboy right.

Aditya has gotten rid of his trademark curly mop for the role.

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

The transformation, according to the director, is startling

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