ATLANTA — After watching a frustrating and unproductive first half of football in the biggest game of the year, Alabama Coach Nick Saban came into the locker room and pulled aside his top two quarterbacks.

He informed them that the sophomore Jalen Hurts, who had started the game — and 28 of the 29 others that he had played in with Alabama — was coming out, and Tua Tagovailoa, a freshman who had never started in a college game, was going in to try to save Alabama’s season.

Hurts had not been playing well, Alabama was getting shut out and Saban needed something to ignite his team in this title game. Tagovailoa provided a spark that turned into a flame and then an explosion of euphoria for Alabama, as his dazzling performance carried the Crimson Tide to a 26-23 overtime victory over the Georgia Bulldogs and a 12th national championship, their fifth under Saban.