Jude Law has said his biggest challenge in preparing for new thriller Side Effects was psychological: convincing himself that he could play a psychiatrist properly.
The Steven Soderbergh movie is showing for the first time at the Berlin film festival, where it's one of 19 contenders for the top Golden Bear award.
Jude plays a psychiatrist who prescribes a new drug he's testing out as part of a lucrative deal with a pharmaceutical giant.
The Anna Karenina star told reporters he was faced with "overcoming the reality that I wasn't going to be able to go to medical school in the time it took to prepare for the part."
He added: "I didn't have a huge relationship with pharmaceuticals or an understanding of them."