Uma Thurman received a "beautiful e-letter" from Charlize Theron before joining the Old Guard 2 cast

Speaking to Extra, Uma shared: "[Charlize] sent me a beautiful e-letter and I read the script, and the first Old Guard was awesome."

Uma was also drawn to the idea of filming more action scenes.

The Kill Bill star said: "I was like, 'Oh, I would be kind of picking up a little bit of my old trope,' and it caught my fancy. I was like, 'I think it's time. I'm gonna go support her and have a big old battle.'"

Charlize relished working with Uma, revealing that she "fell off [her] chair" when the Hollywood star committed to the movie.

Charlize said: "We got on the phone and had a lovely conversation. It was this beautiful mixture of really appreciating the first film we did and then also, like just a real, sincere sense of wanting to support and wanting to collaborate with us."

Meanwhile, Charlize recently revealed that her children are unimpressed by her acting career.

The movie star is one of the best-known actresses in Hollywood - but Charlize's kids are underwhelmed by her achievements.

During an appearance on Jimmy Kimmel Live!, Charlize quipped: "My children have zero respect for me.

"It's just unbelievable, I feel like I'm pretty humble, but every once in a while I'm like 'there's a f****** Oscar right there.' They are so not impressed with me."

Charlize noted that one of her kids is more impressed by another well-known movie star.

The Oscar-winning actress - who has adopted daughters Jackson, 12, and August, nine - said: "My kids were with me when I shot Old Guard 2 and I worked on this incredibly intricate sequence where we brought in this amazing helicopter pilot, Fred North, and we were gonna choreograph this incredible me fighting helicopters and jumping on this real helicopter and hanging off. Shooting 99 percent of it on a real helicopter as it's trying to shake me off like a rag doll.

"We took like two weeks to shoot this sequence and I was like, 'Wow, I just did that, that's really amazing.' And my child yesterday just looked at this poster of Tom Cruise and went, 'It's weird, he looks so much cooler than you did when you were hanging off the helicopter.'"