Michael B Jordon and Sylvester Stallone in Creed New Line Cinema/ Warner Bros

The latest film in the long-running Rocky movie franchise – Creed – is both a spin-off and a sequel, and has reportedly opened to packed houses garnering a lot of praise from fans and critics alike. Director Ryan Coogler recently spoke about the mammoth task of taking Rocky's story forward via a new direction without losing the essence of the original films.

A big part of the job was convincing actor Sylvester Stallone to reprise the iconic character of Rocky Balboa in the spin-off, and on top of that, making Rocky a lot more emotionally and physically vulnerable this time around.

When asked if it was hard to get Stallone on board for this movie, Coogler told Vulture, "It was. But the thing about Sly is, he's an artist, an actor. He's nothing like the characters he became famous for. The only thing he has in common with them is his physicality.

"But he's an intellectual — very articulate. He was definitely apprehensive about the idea of people seeing Rocky like this — and the idea of aging and vulnerability — but at the same time, he was excited about a challenge."

Talking about how he managed to convince the actor eventually, the director said, "It took a lot of time and people," before justifying why it was an important and difficult decision for Stallone to pass over the reins of his most beloved franchise to someone else.

"The legacy of his franchise was so close to him, and the Rocky films have always been inspired by personal situations for him. So handing over the franchise, and bringing the character out of the ashes — which was where he was comfortable leaving him at the end of Rocky Balboa — was the biggest thing to get past," he said.