Teen dreamboat Justin Bieber was booked to appear Saturday night on a popular German game show, but abruptly pulled out of the TV gig after a daredevil contestant, appearing on an earlier segment, was hospitalized when a stunt went terribly wrong during the live broadcast.

Samuel Koch, 23, got severely injured on the set of 'Wetten Dass' ('Bet it?'), according to an Associated Press report, when he strapped on "kangaroo" suspension boots and tried leaping over a moving car driven by his own father.

Viewers of the show -- on which Cher, Phil Collins, Cameron Diaz and Robbie Williams were also among the guests listed on the broadcaster's official site -- saw Koch lay motionless on the studio's floor after he fell midway through his dangerous stunt. Next, host Thomas Gottschalk reportedly called out for a doctor, as cameras panned away.

Bieber, 16, took to Twitter to ask fans to pray for Koch.