Charlize Theron had sparring sessions with Keanu Reeves to get fit for her new movie 'Atomic Blonde'

Charlize said she felt "very macho" fighting against the hunk - who plays the titular lead part in 'John Wick' - and it they had so much fun.

During a Q&A for the premiere of 'Atomic Blonde' at SXSW Film Festival in Austin, Texas on Sunday (12.03.17), she said: "We would kind of spar with each other. I'd be like, 'Come on, Keanu. Let's take it down.' S**t like that. It was very macho. It was great."

The 'Mad Max: Fury Road' star - who has two adopted children, four-year-old son Jackson and daughter August, who was born in 2015 - has found the fitness levels "so hard" and quipped that she looked like Big Bird from children's television show 'Sesame Street' in the gym.

Asked what it was like training for the movie, she said: "It was so hard, are you kidding me?

"When [training] first started I was like, 'This is never going to work, I look like Big Bird.'"

'Atomic Blonde', an adaptation of Antony Johnston's 2012 graphic novel, 'The Coldest City', also stars James McAvoy and is scheduled for release in July.

It is set in Berlin in 1989 and sees Charlize's alter-ego try and track down an espionage ring who are trying to take down her fellow agents.