Mumbai, Dec 5 (IANS): Acting alongside versatile veteran actor Pankaj Kapoor turned out to be quite a challenge for Imran Khan while they worked together for "Matru Ki Bijlee Ka Mandola".

"Pankaj Kapoor as an actor is a very challenging co-star to act opposite, because he improvises a lot and he pulls out new things as they happen. You have to be in the moment with him, you have to be ready with whatever he will do, and you have to be ready to pick that up and take it forward," Imran said.

Besides Pankaj Kapoor, Imran says he was surprised to see the working style of acclaimed director Vishal Bhardwaj. He was especially glad to see the space Bhardwaj gives to his actors.

"I was very surprised by his style of directing. He gives a lot more freedom to the actors than I expected. If during the take, you decide to do something different, he will let you do that. He liberates the actor and puts a lot of power in actor's hands," said Imran, who romances Anushka Sharma in the quirky movie.

The film is slated for Jan 11, 2013 release.