Arjun Rampal was the original choice for the role but he is suffering from a back problem and has been getting the required treatment.
That, however, means he won't be able to perform the stunts in the film. According to sources, Vivek has given an audition for the film and will be chosen in case things on Arjun's end don't work out.
Vivek has been hounding SRK since he knew ‘Ra.One' would start rolling soon. He had his sights set on a Red Chillies project. ‘Ra.One' is a heavy budget film with lots of special effects.