During his career, Donovan played in what many believe was one of the most important games in NFL history, the 1958 NFL Championship Game between the Colts and the New York Giants. The contest between the two teams took place on December 28, 1958, and ended in a 17–17 tie. Because it was the championship game, it went into overtime, the first NFL game to do so. Witnessed by 40 million viewers on nationwide television, the game came to be known as the "greatest game ever played." Donovan made an important tackle during the overtime, stopping the Giants and allowing Johnny Unitas to lead the Colts on an 80-yard scoring drive to win the game. Donovan was one of 12 Hall of Fame players to take part, six of whom were Colts.