At the 7:30 PM performance, Dennehy, who portrays patriarch Ephraim Cabot in the play about property, passion and jealousy, "tumbled from the raised platform of the set to the main level of the set in the scene during which Ephraim thanks God for his newborn baby," according to a statement from the Goodman.

Tony Award winner Dennehy said in a statement, "It was a stupid mistake. I was trying to play beyond my own means and lost my balance."

Dennehy, who fell while holding the swaddled infant (a prop), immediately gathered himself and quipped to the shocked audience: "The baby is not injured!"

Dennehy insisted that the show go on, and he finished the performance to a standing ovation. Though bruised and sore, Dennehy returned to the stage the following day for a noon matinee for students of Chicago Public Schools.

He expects to complete the run, which ends March 1. The Robert Falls-directed staging of the classic has commercial Broadway producers circling. An announcement about a transfer is expected soon.