Can you guess who this actor is?

Here's a hint: He is one of Ranchoddas Shamaldas Chanchad's dearest friends...

R Madhavan -- last seen in a cameo in Zero -- has started shooting his ambitious project, Rocketry: The Nambi Effect.

Madhavan shared his transformation on Instagram and he looks uncannily like ISRO scientist S Nambi Narayanan.

'After 14 hrs on the chair... Who is who is WHO?? #rocketryfilm,' he captions it.

Rocketry: The Nambi Effect is based on Nambi Narayanan's life. The scientist was charged with espionage in 1994. Two years later, the CBI dismissed all charges against him. The Supreme Court finally declared him not guilty in 1998.

Apart from playing the lead, Madhavan makes his directorial debut with the film. Anant Mahadevan, who was to jointly direct the movie, has dropped out of the project.

Photographs: Kind courtesy R Madhavan/Instagram