Ansel Elgort has revealed that his existing friendship with Shailene Woodley helped them during the love scenes in their new movie.
The pair, who play siblings Tris and Caleb Prior in Divergent, reunited to play lovers Hazel Lancaster and Augustus 'Gus' Waters in the big-screen adaptation of John Green's novel, The Fault In Our Stars.
"It was the biggest challenge - no, I'm only kidding. We're actors so that's what we do. It was actually helpful that we got to know each other on Divergent, so it wasn't a problem," the actor said.
"This relationship between Gus and Hazel, it's so important that it's authentic and real and they do feel like they are real friends and they have that chemistry. You should root for them to be together and have this love, and if, in real life these two people don't have any connection, it's just two actors going through the motions and being very boring."
The 20-year-old continued: " So I think because we met in Chicago and did Divergent, Shailene and I became close, became friends and got to know each other. When we did this movie, we were already really close friends and we were able to play off each other and feel comfortable.
"We have little inside jokes that we could have inside our eyes during the scene, and that helps to make it real and authentic."
His co-star Nat Wolff, who plays Gus' best friend Isaac, joked that Ansel would get the names wrong during filming.
"It was hard in all of the love scenes. He would say, 'Hey sis'," he quipped. "I know because I was in the corner with the binoculars."
:: The Fault In Our Stars is in cinemas now.