Karan said Tanay, who played the 'middle' Jamal in the multiple Oscar-winning film, made Shah Rukh Khan's childhood look convincing for the film.
The director chose him to play young Shah Rukh because of not only his facial likeness to the star but also Tanay's instant connectivity with the Mumbai slums and thereafter the Western audience.
'Tanay is exceptionally talented. He was able to imbibe Shah Rukh's character traits and use them to make SRK's childhood look convincing,' said Karan.
The scenes with Tanay were shot in Borivali along with actress Zarina Wahab, who plays Shah Rukh's mother in the movie. The director now intends to cast Tanay as junior SRK whenever required, much in the way that Master Mayur played the young Amitabh Bachchan in a series of films.
Though the take-off point for 'My Name Is Khan' is 9/11, not a single shot is taken in New York. The film is set in Los Angeles and San Francisco - two of the most expensive cities in the US for shooting.
While Karan Johar's production of Rensil de Silva's Kareena Kapoor-Saif Ali Khan film on terrorism will have Philadelphia masquerading as New York, his own directorial take on terrorism and the isolation of the working-class Muslim has gone to two US cities.
Karan shot in LA earlier this year and leaves for San Francisco in May for a 40-day schedule.