Katrina Kaif, recently declared the world's sexiest woman in a poll, is now in a mood to do some serious roles. The actress is all set to shed her glamorous image and take up new roles which will test her acting potentials.

She will be seen in completely different look in Prakash Jha's Rajniti. The film stars Ranbir Kapoor and Ajay Devgan also.

Sources reveal that Jha wants Katrina to have a non-make up look for the major part of the film. Katrina may undergo voice modulation since she is required to speak in a certain dialect in the film's second half.

Katrina says, "My role in Rajniti has different shades - I start off in a particular way and end up as a completely changed character. The character is immensely challenging and it is a huge responsibility to carry it off."