THERE are few bigger stars a young actor could hope to work with than Angelina Jolie.

Jack O'Connell is now firmly in the spotlight as the lead of Jolie's latest film Unbroken, which premiered in Sydney last night.

The 24-year-old walked the red carpet alongside Jolie, her husband Brad Pitt and his co-stars at the star-studded event.

"She's fully supportive. Even up until last night throughout all of that madness she just leads by example," O'Connell told APN.

"It's because of her dedicated leadership and under her captaincy I was capable (of playing the role).

"She's so maternally instinctive."

The war movie, which was filmed in Queensland and in Sydney, is already creating Oscar buzz.

It is a career-changing role for O'Connell, who was locked in a cell and hit with a rubber baton as part of his screen testing.

"I was pretty adamant I was going to make sure it went my way, even if I had to take a couple blows," he said.

"It was definitely eye-opening, but I don't deserve any sympathy."

The Skins star went through a dramatic weight loss to portray war veteran Louis Zamperini's 47 days lost at sea and his subsequent interment in a Japanese PoW camp during the Second World War.

"I have not stopped eating since I've been here," he said.

"The food here is so nice. I didn't get to enjoy it last time."

Unbroken opens in the US on Christmas Day and in Australia on January 15.