The director feels that it's such a big franchise starring Salman Khan and Katrina Kaif, but more so after 'Sultan'.
Mumbai: Filmmaker Ali Abbas Zaffar is ready with his next project 'Tiger Zinda Hai', but says the film wasn't written as a sequel to 'Ek Tha Tiger'.
'Ek Tha Tiger', released in 2012, was directed by Kabir Khan and featured Salman Khan and Katrina Kaif as agents.
The second installment of the action-drama is helmed by Ali, who previously directed 'Sultan'.
"When I wrote this film, it wasn't like a sequel. I first wrote the story and felt it was worth telling. I thought since it's about two agents - and we already had a film about two agents with Salman and Katrina - I'll merge these two in this story so that it becomes a story of two characters which people already know," Ali told reporters here.
He was speaking at the trailer launch of 'Tiger Zinda Hai'.
The director said he feels tremendous pressure to take the franchise ahead.
"There's a lot of pressure. Obviously, it's such a big film with Salman Khan and Katrina Kaif. It's a big franchise and I did 'Sultan' with Salman, so there's an added baggage," he said.
The film chronicles the story of two agents on a mission to rescue 25 Indian nurses taken hostage in Iraq by a terrorist organisation.
Ali said they have based the film on a true story but have fictionalised it a lot.
"When they (Salman and Katrina) heard about the story and I told them about the rescue mission, what happened in those ten days when the nurses were captured, they both felt excited. It's a completely fictional account, it's a fictional film which we have written around the event, how these two get those nurses back," he said.
Ali said the sequel is very different from 'Ek Tha Tiger', which was more romantic.
"It's very different from the first part. The first one was romantic, whereas this one is about a mission. In 'Ek Tha Tiger', you saw them (Salman Katrina) as lovers, here you'll see them as agents. The action is more real and gritty. We have spoken about relevant things in today's times which are affecting us," he said.
This is Ali's second film with both Salman and Katrina after 'Sultan' and 'Mere Brother Ki Dulhan' respectively.
The director said it was easy to convince both of them as they "reacted very strongly to the story of the film."
"The equation is the same. Somewhere it's a good relationship. We have worked together very well. He is such a big superstar and there is a certain way people like to present him, perceive him," he said when asked about his equation with Salman.
"I think somewhere between him and me, we have the understanding that I kind of look at him in the way that people want to look at him - as the quintessential hero. He is not a superman, he is real yet at the same time he can do what we want him to do," the filmmaker said.
The film is scheduled to release on December 22.