Mumbai: Oscar winner composer A R Rahman says his upcoming project '2.0,' starring superstar Rajinikanth and Akshay Kumar, is a tough film to work on.

"It is the toughest film I am doing. Shankar (director) is not happy with anything I am doing. I am trying to create something unique for India and the world," Rahman said.

The composer had collaborated with S Shankar for the 2010 science fiction drama 'Enthiran' ('Robot' in Hindi) with Rajinikanth, Aishwarya Rai Bachchan and Danny Denzongpa in lead roles.

Even the southern superstar, Rajinikanth, feels it is a tough job to please Shankar.

"To work with Shankar is difficult. He is a perfectionist. That is why he is one of the biggest directors. This picture as 3D is a different experience," the 65-year-old actor said.