Ryan Reynolds knew actress Zazie Beetz would be a perfect fit for his Deadpool sequel just seconds after the pair met during her audition.

The Atlanta star portrays lucky mutant Domino, also known as Neena Thurman, in the sequel to 2016's hit action movie, reportedly beating out the likes of Kerry Washington and Sienna Miller for the coveted gig.

And leading man Ryan, who also serves as a co-writer and producer on the new Marvel project, reveals he was so impressed by her take on the comic book character, he was instantly won over.

"She read for the role and like, two or three words into it, I remember looking over at our brilliant director David (Leitch) and just going, 'Oh oh oh oh...!' She's incredible."

Ryan and David broke the news to Beetz in an early morning phone call not long after the try out, and she was so stunned, she shed tears of joy.

"I was (surprised to be cast), I know they were also testing with a bunch of other great people so I definitely, genuinely was very surprised," she smiled on breakfast show Good Morning America.

"On the day I found out, Ryan was texting me in the morning and I was like, this is suspicious and early, and then him and the director Dave called me and... I think I cried a little..."

When the news of her addition to the Deadpool 2 line-up emerged last year (17), a number of Marvel fans took to social media to question the casting, as Domino is typically portrayed in the comic books as a white woman, and Beetz is of African-American heritage.

However, she did her own research into the mutant hero and declared, "I want to point out there was never a race assigned to the character, at least according to the creator, but yes, I look very different from the comic version."

Deadpool 2, which also stars Josh Brolin as Cable, opens in theatres this week (ends18May18).