Sylvester Stallone spoke about the ‘devastating’ death of his son Sage – and their strained relationship  – in his new Netflix documentary Sly.

Sage, who died at 36 of coronary artery disease in July of 2012, played the role of Rocky Balboa’s son Robert in the 1990 motion picture Rocky V.

In the storyline of the sequel, Sage’s character Robert felt neglected as his father focused his efforts on mentoring young boxer Tommy Gunn, played by the late Tommy Morrison.

In the streaming documentary, the 77-year-old actor makes a number of personal revelations, saying said that ‘unfortunately,’ aspects of the Rocky V plot were harvested from the real-life relationship between the pair.

Stallone, who penned the script for the film, which also starred Talia Shire and the late Burt Young, said that he would be inspired in his writing to put his characters into places he had aspired to be.

Details: Sylvester Stallone, 77, spoke about his relationship with his late son Sage (pictured) in his new Netflix documentary Sly

In the storyline of the sequel, Sage’s character Robert felt neglected as his father focused his efforts on mentoring a young boxer Tommy Gunn, played by the late Tommy Morrison

‘I try to take something that actually is what I wish I had done in real life, but I wasn’t able to do that in reality,’ the three-time Academy Award nominee said. ‘And so quite often I would do it theatrically, magically… a lot of that is true.’

At the time of the film’s release in November of 1990, Stallone was coming off a scorching run in his career with a decade of hits, including multiple films in the Rocky and Rambo franchises.

‘Unfortunately, you put things before your family,’ he said in the doc. ‘And the repercussions are quite radical and devastating.’

Speaking with People in 1996, Sage acknowledged the art imitating life aspect portrayed in Rocky V, citing a scene in the movie in which he fought with his father.

‘When I was screaming, “You never spent time with me! You never spent time with my mother,” that was true,’ he said. ‘I was looking into my father’s face and really saying that.’

Sage said that ‘after the film, everything changed’ with him and his father for the better.

‘I got a lot of things out,’ he said. ‘We broke into tears a few times. We’d do anything for each other.’

Sly includes footage from a premiere of Rocky V in which he and his son walked the red carpet.

Details: Sylvester Stallone, 77, spoke about his relationship with his late son Sage in his new Netflix documentary Sly

In the streaming documentary, the 77-year-old actor said that ‘unfortunately,’ aspects of the plot of the 1990 movie were harvested from the real-life relationship between the pair

Stallone, who penned the script for the film, said that he would be inspired in his writing to put his characters into places he had aspired to be

At the time of the film’s release in November of 1990, Stallone was coming off a scorching run in his career with a decade of hits, including multiple films in the Rocky and Rambo franchises. Father and son are pictured together at the Rocky V premiere in West Hollywood in November 1990

‘There’s a line in the movie, “I’m so glad he’s born because now I can live through your eyes,”‘ Stallone said at the premiere, as seen in the doc. ‘That, I think, is what fathers look to their children for. It’s an extension of a slice of immortality.

‘As long as he’s alive, your memory will always be alive, that you did something right. I mean, you hope for that.’

In August of 2012, Stallone told Good Morning America that it was ‘very tough’ as he dealt with the loss of his son.

‘Time, hopefully, will heal, and you try to get through it, but it’s just something,’ he said. ‘It’s a reality of life. I think it’s important to get back and start reliving your life. Otherwise, you can go into a spiral.’

The Tulsa King star is also father to daughters Sophia, 27, and Sistine, 25, and Scarlet, 21, with wife Jennifer Flavin, 55. He has two sons with first wife Sasha Czack, 73 – Seargeoh, 44, and Sage.

Stallone on Tuesday took to Instagram to thank viewers of the doc, which debuted earlier this month.

‘Thank you to everyone who has watched SLY on @netflix,’ he said. ‘I’m overwhelmed with the reaction and glad you guys have enjoyed it. Keep punching.’

Sylvester Stallone, Sage Stallone and Jennifer Flavin were pictured in November of 1995 in Paris

Stallone on Tuesday took to Instagram to thank viewers of the doc, which debuted earlier this month

In an accompanying clip, he said, ‘Hello everyone, I’m outside talking to the birds … I want to thank everyone for tuning in to the Netflix documentary.

‘It was quite a surprise and a revelation, because I didn’t expect the reaction, and I guess if you feel relaxed enough, you start to talk and before you know it, the layers peel away, you start to reveal a lot of yourself that you weren’t ever expected to do.

He added, ‘Sometimes those things are just covered away because people – you shed your skin, and you go on and be a different personality – I don’t think we ever shed our skin, I just think it gets thicker and thicker and thicker and thicker.

‘And quite often, when the opportunity presents itself, you dig down and you revisit yourself and why you’re like you are.’

He wrapped up in saying, ‘Keep punching,’ adding, ‘Take care, thank you.’