It's Arjun Rampal vs SRK once again. The actor who is said to be suffering from persistent back problem has replaced Vivek Oberoi as a villain in Shah Rukh Khan's sci-fi thriller Ra.1.

Though Arjun has been the first choice for the role, his availability for it was doubted because of his continuing back problem.

So much so that Vivek Oberoi was briefly considered for the part and he even auditioned for it. But finally Arjun has recovered and is fit to make a comeback.

According to a source, "Arjun was always the original choice to play the villain. Director Anubhav Sinha was very keen to have only Arjun because he perfectly suited the role and his persona is exactly what the director was looking for. His back problem was the only hurdle."

Though Arjun will perform a couple of stunts, but being a SFX movie, the director will make things easier for Arjun through the use of technology.