Krieger had three important bouts with Billy Conn, who would take the Light Heavyweight Championship after their last bout. In their first bout on December 16, 1937, he won decisively by unanimous decision in Pittsburgh in twelve rounds. Billy Conn later said of the bout, "This guy Krieger was the toughest...I ever fought. I ached for a week after my first fight with him. He could lick anything around now." In their second bout on November 28, 1938, again in Duquesne Gardens, in Pittsburgh, Krieger lost by unanimous decision in twelve rounds.