Tom Sizemore found his own private hell at the end of a needle. And it took some tough talking by one of the toughest stars in Hollywood to make him confront the demon that was destroying him.

The crunch came when Tom had been co-starring with his friend Robert De Niro in Heat. Rather than shake hands after filming, De Niro booked Sizemore into a drug rehabilitation clinic.

Even then, knowing that it was a matter of his own life and death, Tom couldn’t bear to confront the truth. Instead, he ran away and hid in a hotel bedroom. De Niro finally found him and delivered a line which could have come from one of his movies: “You can walk out of here and I will have you arrested for heroin possession … or you can go to this place in Arizona and stay there until you get better.”

Tom, 34, chose Arizona.

De Niro flew him there on his own private jet – and delivered him to the front door. And as Tom started to confront his demons, De Niro was always there on the end of the phone, nagging, probing, checking up. “He used to say to me, ‘Don’t you wanna wake up and know what the hell you’re doing? ‘Don’t you wanna remember what you did last night? He kept going on and on.”

That nagging was necessary. Gossip magazines had been hinting at drug abuse, and then Tom was arrested.

“It was no use pretending that I did not have a problem.”

Ton, whose film credits include Natural Born Killers, Devil In A Blue Dress and Strange Days, was a reformed character when Spielberg offered him the role in Saving Private Ryan.

And he will never forget what the legendary director said to him, “He told me, ‘You have done a great job in other movies, but you’ve only been given part of the piano to play. I want to give you the whole piano and want to see you playing all the notes.’

“He said I had the potential to be a leading man, which was flattering. De Niro is always telling me. ‘You are so young, you don’t know how young you are’,”

Maybe it was the years of drug abuse or maybe it was simply the shock of a soldier’s regime, but Tom found his week’s training under Captain Dale Dye almost more than he could stand. He remembers doing a five-mile run, in full military gear – and being ordered to keep running even when he had vomited.

“On reflection it was the best think for me. It also taught me something of what it was like to be in that situation.” “Those guys had to do the tough training – then go out and fight a war. It must have been terrifying and makes my problems seem pretty small.”

Tom stuck with the training, realising that the need to prove himself to his friend, as well as his director, was all-important. “I had been given a once-in-a-lifetime chance by Spielberg and I didn’t want to blow it.” He said. “He is a genius – an over-used word in Hollywood which probably applies to just him … and Robert De Niro.”

Tom’s role as Sergeant Horvath is a complex one, because he is not just a soldier – he is also a friend of the Tom Hanks’s character, Captain John Miller.

“In scenes where they are alone, they call each other by their first names,” he says.

“Only Marines who know each other well would do that. The two have been together serving for three years in Italy and Africa and are just falling apart with all the action they have seen.

“The first shot in the movie is Tom’s hand shaking as he goes for a water canister. The camera goes up to him and then to me, putting tobacco in my mouth. The involuntary shaking is the first sign of shell shock.

“In the movie, my purpose is to keep him alive and make sure that the men don’t see that he is falling apart.”

Tom shudders slightly at the thought – he knows how close he came to falling apart in real life, and how only his friend De Niro saved him from wrecking his life.

“I though drugs helped me be intense,” he says. “But that was just rubbish.”