Some guys have plenty of confidence in their old friends ... can you guess who this former professional wrestler is?

We ran into this dude while he was signing autographs and asked him if he had any advice for his old pal John Cena as he prepared to leave the ring behind ... but he was confident his buddy had a pretty bright future outside of wrestling.

And don't worry about him, because he's staying busy, too ... sharing the screen with Jason Momoa doesn't sound like an easy feat, though!