Shailene Woodley has revealed she felt a lack of screen chemistry with her Divergent co-star Theo James at the start.
The 22-year-old, who stars as Tris Prior in Neil Burger's big-screen adaptation of the first novel in Veronica Roth's book trilogy, admitted she had initial doubts about the British star, who plays her mentor and love interest Four.
"One of the reasons I didn't really feel we had that much chemistry in the movie... was because we didn't really get to improv (improvise)," she said.
"In movies past... we were able to improv a lot so I think that really helps lend a natural chemistry that you're aware of because you're depending on the other person."
The Golden Globe-nominated actress added: "Luckily, our scenes were filmed chronologically so as we got to know each other and as we got to be more comfortable around each other, our characters were as well. Watching the film, it's evident but filming it, maybe that's why - in the beginning scenes."
Theo added: "You never really know per se because you're matched in the scene. You can tell when there's not (chemistry), I think."
The pair admitted the shoot, which took place in Chicago over three months, was quite intense.
"We got to hang out but to be honest, it was pretty intense especially for Shai. She's in every scene in the movie so it was fairly go, go, go," Theo said.
:: Divergent is in cinemas now.