Matt Damon shut down production on his first ever acting job after tripping over his ice skates and knocking himself unconscious.

Damon was cast as a young Michael J. Fox in a local Massachusetts Tv show and tasked with showing off his ice hockey skills as the Back to the Future star once did in high school.

But after exaggerating his athletic ability during an audition with producers, the Good Will Hunting hunk was severely injured on the first day of filming after falling on the rink and bumping his head.

He tells U.S. Tv host David Letterman, "My first acting job was to portray a young Michael J. Fox on a local show... So they (the casting agents) came to our school, and... auditioned everybody.

"I was 13, I was a freshman and I got the part. It was a very, very big deal for me, and I was gonna get a couple hundred bucks. And then they said, 'Can you ice skate?' And I was like, 'Sure,' (because) I had roller skated...

"So I went and I was practising wobbling around there and they called me back to the set. They were ready to do a shot that required me, at speed, (to be) turning around and skating back at them. And so I tried to do my roller skating cross-over move, and with the roller skates you had four wheels and a bigger base there, and so I caught an edge and dropped directly to the ice and slammed my head and knocked myself out cold.

"This was my first professional day, but I actually shut down production."