Marcus Mariota's breakout season as the Titans' second-year quarterback has come to an end.

With it, any limited hopes of Tennessee winning the AFC South are gone, too.

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QB Marcus Mariota Injury
— Kyleah Jasmine (@kyleahjasmine)

Titans coach Mike Mularkey after the game said Mariota suffered a fractured fibula, and the quarterback indeed is out for the season.

Mariota was trying to rally the Titans from a 25-10 deficit after a bad near three quarters (8 of 20, 99 yards, INT) against the Jaguars' top-five pass defense. He was quickly ruled out from returning to the game.

Backup Matt Cassel had to take over for Mariota for the final quarter-plus. He immediately led a touchdown drive to make it a one-possession game.

Mariota being out might not matter much since the Titans lost to the Jaguars. It put the Texans in position to lock down the South title with a home win vs. Cincinnati on Saturday night — well before the teams play next Sunday.