The theatrical trailer of Balaji's upcoming film "Once Upon A Time in Mumbaai" was released alongside Anurag Basu's "Kites" Friday. Directed by Milan Luthria, "Once Upon A Time in Mumbaai" traces the changing face of the Mumbai underworld. The film, set primarily in 1970 Mumbai, follows the rise of Sultan (Ajay Devgn) and his eventual fall when his protégé Shoaib (Emraan Hashmi) challenges his supremacy and usurps power to rule the murky underbelly of Mumbai. Sources revealed that those who have seen the rushes of the film can't stop raving about it - thanks to its slick, clutter -breaking approach of mirroring reality something that the makers are known to do with élan. In fact, when the trailer was played on the big screen, audiences were seen whistling and hooting especially in multiplex theatres in the suburbs. "In the day and age where production houses are churning out one comedy and romantic flick after another, Balaji dares to be different and comes out with a slick and entertaining film that makes you re-live the iconic days of the Mumbai of 1970s, " a source said in a statement. Balaji and Milan Luthria's "Once Upon a Time in Mumbaai" is all set to release worldwide July 30.