London: Hollywood star Robert Downey Jr decided to do the road movie `Due Date` after he came to know that Zach Galifianakis will co-star in the movie, says director Todd Phillips.
The `Iron Man` star seemed to be a "fan" of Galifianakis, who gained immense popularity for his portrayal of Alan in `The Hangover`.
"I think Robert was a fan of Zach`s and he was also a fan of the irreverent attitude we wanted to take the script in," Phillips said.
"The film is less about a road trip though, the appeal of the road trip as a film maker is you get the two characters and put them out there without a safety net, without their friends and family around them and just put them out there flying without a net," he added.
However, Downey has said that he may never be able to take a road trip with Galifianakis again.
"The likelihood of Zach and I ever being in a car alone together again, is next to nothing," said the actor.
Meanwhile, Zach feels his job as a comedian has made others constantly think of his actions as antics, making them laugh, even as he experiences reflective moments in his life.
"If you`re known as a funny person, even in real life, whether you`re an actor or not it`s hard to be taken seriously.
"I was at my sister`s wedding and I started crying as I was giving her a toast and everybody was laughing at me crying which is the worst feeling in the world, so I do have this chip on my shoulder about `goddammit, you`d better start taking this seriously,`" the actor said.