To follow up their hit comedy Crazy Stupid Love, writer-directors Glenn Ficarra and John Requa have merged the con-artist heist thriller with the romantic-comedy genre; a move that was Will Smith's first encouragement with getting involved with the movie.

Will Smith and Margot Robbie in Focus
Will Smith and Margot Robbie star in 'Focus'

Will Smith was drawn to the material both because of the filmmakers and the subject matter. "When I read Focus it was so interesting because it's so many different kinds of movie," he said. "Glenn and John completely ignore genre, so it's a heist film but then it will be a bizarre comedy for awhile and then it's really serious and there is great action. And then there's a wonderful love story in the centre of the film. We would be in scenes sometimes and we would be like, 'This is serious right?' and they'd be like, 'Yeah, but have fun with it.'"

More: Read our review of 'Focus'

Margot Robbie was drawn to the lead role as Jess because she's such a complex character. "There was lot to do for Jess, because halfway through she's a woman scorned and then she transforms after that, so they develop it really well," she said. "It's really nice to have a character that has one starting point and is a totally different person by the end of the film. It's kind of nice to play with that, so I was lucky."

Watch the trailer for 'Focus' here: 

Robbie also enjoyed the chance to learn how to pick pockets in a crowded street. "It's a lot harder than it looks," she said. "But the more you look into the psychological side of it the more the physical side makes sense. To begin with, you can't believe that you could steal something in plain sight. When [our pickpocket advisor] explained about distractions and things like that it made the physical side of things a lot easier."

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Smith agrees. "The psychological side - the human side - you just can't imagine that the human brain is that feeble," he said. "We think that we're aware and we're paying attention, but we have such huge blind spots!"