The renowned director Ang Lee has made one of his boldest films yet: "Gemini Man" is a sci-fi action thriller that pits 51-year-old Will Smith against a 23-year-old clone of himself.

One of the most recognizable stars in the world, Will Smith admitted that playing a deadly assassin who goes into battle against a younger version of himself was quite a challenge.

Will Smith and "his admirable director" Ang Lee attended a press conference in Shanghai ahead of the film's release in more than 600 IMAX cinemas in China on Friday, October 18.

Lee said he was attracted to the story of "Gemini Man" in part because its compelling hook, that of a man fighting his younger, fitter doppelganger, required an enormous technological investment.

"Will Smith junior, which was made using a digital knife, is two to three times more expensive than what we paid the famous American actor himself," said Ang Lee. "It's the most expensive actor in Hollywood."