Viggo Mortensen embraces the ''ugly side'' of characters, according to Hossein Amini.

The 'Lord of the Rings' star plays organised criminal Chester MacFarland in the big screen adaptation of the Patricia Highsmith novel 'The Two Faces of January', and his director believes he was the perfect choice.

Speaking about Mortensen's ability to bring out the dark side of human nature, Amini told Variety: ''I love the cruelty in her [Highsmith's] writing. Viggo really embraces the ugly side of characters ... not a lot of stars do.''

Amini - who made his directorial debut with the film - claims it was a joy to work with Mortensen and his co-stars Kirsten Dunst - who plays his wife Colette MacFarland - and 'Inside Llewyn Davis' star Oscar Isaac, as they needed little direction.

He said: ''I learned to say as much as possible by saying as little as possible.''

The 48-year-old director was a university student when he first began reading Highsmith's novels such as 'Strangers on a Train' and 'The Talented Mr. Ripley' and he's confessed he's wanted to make 'The Two Faces of January' into a film for over a decade.

Mortensen currently has a number of films in post-production, including 'Mojave', 'A Most Violent Year' and 'Ex Machina'.

The 55-year-old actor previously admitted he wasn't interested in starring in box office hits as he's motivated by good storylines.

He said: ''''I don't care whether it's a blockbuster or not ... I'm not worried about it.''