George Hamilton's actor son has his longtime pal Robert Downey, Jr. to thank for helping him bag a role in Iron Man 3.

Ashley Hamilton struggled to get his Hollywood career back on track after overcoming his drug and alcohol addiction problems, and admits Downey, Jr.'s vote of confidence gave him the boost he needed.

Hamilton explains, "He helped open the door (to work on the movie) but he said, 'I can't do it (all) for you, dude.' I said, 'That's Ok. I just need somebody to give me the opportunity to trust in me sober-wise and give me a shot of this magnitude.' I'll forever owe him for that...

"(I'm) really grateful for somebody giving me an opportunity again. I just didn't have that before."

The 30 year old, who plays former military officer Jack Taggert in the Marvel blockbuster, is now working on upcoming movie Tranzloco and a play.