Mumbai: Aamir Khan and Abhishek Bachchan unveiled the trailer of much-awaited action thriller “Dhoom 3”, but the film's leading lady Katrina Kaif skipped the event. When asked about the actress, Aamir kept it secret as he said, “I can't say where Katrina is, it's a secret."(photo courtesy- Vinod Singh)While it is rumoured that Aamir Khan has decided to keep Kat away from the promotional events, it is reported the actress is currently in Beirut shooting for Kabir Khan's next.During the launch Aamir also shared his experience with reporters. He said, “Every film is challenging, but this was a tough role. I had a great time working in the film.”In terms of preparation, the actor had to workout a lot for "Dhoom 3"."I am playing a gymnast in the film. I also went for circus training for the film. There was a lot of hard work for the film. I followed a strict diet."Director Vijay Krishna Acharya's film is sleek and stylish and going by the trailer, it can wow the audiences when it comes out Dec 20.Abhishek, who is working with Aamir for the first, praised his co-star."Aamir has done a brilliant job. It's a very memorable film. Uday and I are like juniors in front of him. His passion for films is wonderful. It was a learning experience to work with Aamir," said Abhishek who has been part of “Dhoom” franchise since beginning.He will reprise the role of ACP Jai Dixit in “Dhoom 3”, who is trying to trap Aamir's character.Dhoom 3 is slated to release on December 20th this year.