Sharon Osbourne and David Hasselhoff's U.s. TV talent show has suffered its first casualty.

Acrobatic dancer Ivan, who wowed the celebrity judges with his moves early on in the America's Got Talent season had to be taken to hospital during a recent show when he knocked himself unconscious.

The wannabe fell awkwardly on his head while trying to jump over a line of metal chairs during the final elimination heat of the show.

Host Jerry Springer says, "He made the leap and everything and then he didn't get up and I thought, 'Oh boy, this looks bad.'"

"At first, everyone thought it was part of the act. It's not part of the act."

The show was halted as production staff and medics attended to the dancer. An ambulance was called as Ivan came to. He was taken to hospital for tests.