In her first-ever stage performance, big-screen cutie JESSICA BIEL wowed the crowd in "Guys and Dolls" at the Hollywood Bowl, then got bowled over when she made a wrong offstage exit – and smashed into co-star SCOTT BAKULA, who was just making an entrance.

Shocked Scott shook it off and walked onstage, but gob-smacked Jessica swayed and collapsed against a wall, looking like she’d been hit by a truck, until a stagehand guided her to her dressing room.

Catching her breath for a few minutes, brave Biel applied ice to a red welt on her forehead, then went back onstage like a trouper and finished her performance to wild applause.