The new Karan Johar magnum opus "Kabhi Alvidaa Na Kehna" will finally take off Thursday. .

The launch will be attended by Karan's very close family and friends, including the Bachchans and the Khans. The senior Bachchan, who plays the most rakish role of his career in the film, will give the first shot.

From the film's controversial title to the atypical theme, "Kabhi Alvidaa Na Kehna" has been under media and showbiz scrutiny for months. After months of toil in London, Karan has got the screenplay in place..

"It's been a hectic time. I feel I've to take an appointment from myself to meet myself. First the script was a huge problem. Since I was going into unexplored territory - the various facets of the man-woman relationship in an urban setting - I encountered many stumbling blocks while writing the script," told Karan.

"The Hindi dialogues had to be authentic and real, and yet conversational...a hard task. Then getting the vast cast in place was a problem. Finally, I've got Veer-Zara (Shah Rukh Khan-Preity Zinta) and Bunty-Babli (Abhishek Bachchan-Rani Mukherjee).

"But above all, I have Bachchan. No one else could play his role."

The first two weeks of Karan's film will be shot in Mumbai. Then he moves to the US for the principal shooting of what's touted as a departure for Karan Johar from his style of filmmaking..

But Karan protests: "Hey hold it! Enough of this departure theory. 'Kabhi Alvidaa Na Kehna' will be a typical KJ film.

"It will be large in canvas and scope and hopefully in emotions. It will be the 'Kabhi Khushi Kabhie Gham' (K3G) located in the heart and other intangible regions of the human being. Yes, it's different from my other films.

"But was K3G anything like 'Kuch Kuch Hota Hai'? And did 'Kaal' resemble 'Kal Ho Na Ho' in any detail? Have I made my point? Then let's move on."