The quarterbacks likely will call an audible. There are generally four ways to call an audible. Most teams use a number code. If the first number is the snap count, the quarterback is changing the play.
Teams also use color codes and hand or foot signals to alert receivers to change their patterns.
In the National Football Conference Championship Game, the Packers called an audible when Favre recognized that the Panthers were in an all-out blitz in the first quarter. The rest of the way Favre was able to audible successfully when he noticed that the Panthers were going to blitz. It was in the quarterback's hands to audible and get the protection that he needed. The audible has a colorful history. He thought the huddle was just a way to delay and stall the game.