Actor Aamir Khan, who would be seen as a baddie in the third installment of hit film series 'Dhoom', says, he is not mentally prepared for the film.

"I have started preparations for "Dhoom 3". For my role I have began working on the physical side. But I am not mentally prepared yet," Aamir told reporters here.

"Dhoom" series centres around bike chases, handsome thieves and daring theft plans. After the success of "Dhoom" (2004) and "Dhoom 2" (2006) there is a lot of buzz around the third movie.

Aamir would play the bad guy while Abhishek Bachchan and Uday Chopra would reprise their roles of Jai and Uday respectively.

The 47-year-old actor would feature opposite Katrina Kaif in the film, directed by Victor Acharya and produced by Aditya Chopra. It is set to hit cinema houses in 2013.