Sylvester Stallone will be returning to one of his classic action hero characters later this year in Rambo V: Last Blood. It will be the first time in over a decade that Stallone has played the character of John Rambo, but based on the testimony of his co-stars, the actor hasn't lost a step. In fact, quite the opposite, Stallone is a consummate performer and ever the professional.
Dimitri Thivaios is one of those costars and according to him, he learned more about acting watching Sylvester Stallone work than by actually taking classes. According to Thivaios...
[It] was amazing — he’s a hard-working , true professional that sees everything happening on set. You just get sucked into that vibe. I learned more from watching him work him in the time we were shooting than I did in all my years of acting class.
Sylvester Stallone shares a screenplay credit on Rambo V: Last Blood in addition to starring as the lead, so he's much more than simply an actor here. However, it seems clear based on Dimitri Thivaios' comments that Stallone had almost a director's perspective on the film, paying attention to everything that was happening on set. While Stallone isn't the director here, he's had more than his share of experience in the job, and thus probably uses those skills at all times.
Dimitri Thivaios is fairly new to acting, having made his career in the music industry under the name Dimitri Vegas. He's had a few roles in film and on TV in the past but they've been pretty small parts up until now. Exactly what role he's playing in Rambo V: Last Blood has not been revealed so it's unclear if it's another bit part or something more substantial.
While the Rambo franchise doesn't have quite the passionate fan base that the Rocky movies have had, it is still a well loved character. Dimitri Thivaios himself says he has a particular attachment to the film as tells Variety that First Blood, the original film in the series, was likely the first action movie he ever saw as a kid.
He had to see it behind his mother's back, which isn't surprising. First Blood isn't just a bloody and violent action movie, it's fairly disturbing one, as, while John Rambo is the hero, he's also a man dealing with some serious issues as a result of his service in Vietnam.