Joseph Gordon-Levitt achieved a ''glorious victory'' when Bruce Willis complemented him on his acting abilities.
'The Dark Knight Rises' actor plays a young version of Bruce's character in 'Looper' and was astounded when the 'Die Hard' star said good things about his abilities on set.
He explained: ''He's a very understated guy, which I admire. It means you know he's being honest.
''But we were doing a scene where we were yelling at each other and between takes he said, in his off-the-cuff manner, 'Ah, you sound like me.'
''That was a moment of glorious victory for me. I kept it cool, I didn't want to embarrass myself, but I was grinning ear to ear on the inside.''
Joseph, 31, also described how he studied Bruce's acting technique by watching his films and studying his voice and body language, to ensure his portrayal was accurate.
He added: ''I watched his movies a lot, but I focused on the recent ones. I was less interested in coming off like a young Bruce - I was interested in matching him now.
''Making sure audiences understood these two are the same man. I would also rip the audio off the movies so that I could listen to his voice on my iPod.
''In fact, he even recorded himself doing some of my voiceover monologues and sent them to me so I could hear what it would sound like in his voice.''
In 'Looper' Joseph and Bruce's character, Joseph Simmons, is transported into the past as part of a complicated gangland plot which sees him targeting himself.