Chris Pratt requested to be locked in executioner's chair for Mercy

Chris Pratt asked to be locked in an executioner's chair for his role in Mercy.

The 46-year-old actor stars in the new sci-fi action thriller as homicide detective Chris Raven - who has just 90 minutes to prove his innocence to AI Judge Maddox (Rebecca Ferguson) after being accused of murdering his wife - and revealed that he asked director Timur Bekmambetov to keep him trapped in the chair to add authenticity to his performance.

Chris told BBC News: "I thought this would help lend itself to the performance, and feelings of claustrophobia and being trapped.

"I was sweating, so if my face itched, I couldn't scratch it, and I couldn't get up."

Mercy is a departure from Pratt's usual roles but he accepted the part because he wanted to test himself as an actor.

The Guardians of the Galaxy star said: "I'm always eager to try new things, to be challenged in different ways, and maybe give audiences something they might not expect from me.

"I couldn't rely on the thing I like to bring to roles - where I'm a little bit goofy and guileless. This is serious."

Chris revealed how his scenes with Ferguson were shot as he was several feet above ground in the chair and meant that he couldn't see his co-star when the pair were filming.

He said: "Rebecca was there. I was listening to her voice, but she wasn't on set with me.

"So being isolated in this big box by myself was just a really great challenge."

Mercy does feature action scenes away from the court and Pratt explained that it was if he was filming two different projects simultaneously.

The Super Mario Bros. Movie star said: "It was almost like shooting two movies at once.

"So the 10,000 things that I'm confronted with through the course of this trial, we shot all of that stuff. "

Chris revealed that he found the project a lot more "fulfilling" than a typical film shoot.

He explained: "When you do these big blockbuster movies, they're really fun to sit down and watch. But making them can be really tedious, because you spend an entire day doing something that might be 15 seconds on screen.

"The next day you're doing another piece entirely, and it's all very disjointed."

Mercy addresses the growing influence of AI in society and Pratt explained that he is "cautiously optimistic" about what the technology can do.

He said: "I'm not a total doomsday type of guy.

"I'm cautiously optimistic about these evolving technologies, and how they might actually move humanity forward in a great way."