Joseph Gordon Leavitt plays a young Bruce Willis in “Looper” a time-bending thriller presented at Comic-Con on Friday, July 13 in which the actors are past and future Joe, an assassin sent back in time to kill his older self, TheWrap said.

While the character is named “Joe,” Gordon Leavitt actually is playing tough-guy Willis, facing himself down in clipped, understated dialogue, and with a surprising resemblence to the older actor.

It was not easy, the actor explained. He spent three hours a day in make-up having prosthetics applied that would suggest Willis, and he spent hours listening to Willis’ dialogue in old films.

“I’m not a good mimic, I don’t do good impressions,” said Gordon Leavitt at the panel presentation in Hall H on Friday. “I didn’t think an impersonation would be distracting, but I tried to internalize him and do something that made sense.”

He put Willis movies on his iPod, but “the most I learned was by hanging out with him,” said Gordon Leavitt. “He’s a super cool guy. He loved this job. He was clearly there to play.”

Willis didn’t make it to Comic-Con this year, but the director Rian Johnson was there along with Emily Blunt.

Johnson wrote the part for Gordon Leavitt, who is a long-time friend.

But, he said, “After we cast Bruce we realized, uh-oh they don’t look anything alike.” The movie will be out in late September.