The Titans mounted a furious second-half comeback, led by quarterback Marcus Mariota, who went 19-31 with 205 yards and 2 touchdowns, and running back Derrick Henry who rushed for 156 yards on 23 carries.
The Titans got on the board with a 49-yard field goal by Ryan Succop, but Kansas City made it 21-3 in the final seconds of the first half on a 14-yard scoring pass from Smith to Demarcus Robinson. The Titans needed a win in their regular-season finale and some help to earn a wild-card spot as the AFC's fifth seed. With the score at 21-16, the Titans lined up for two, but they ran a terribly designed play that gained one-yard and would've been nullified by an Illegal Shift penalty regardless.
As multiple Kansas City defenders ran at him near the line of scrimmage, Mariota saw an open man in the end zone and threw the ball.
His counterpart, Marcus Mariota, was 7 of 13 for 82 yards with no touchdowns and an interception.
Check here for injury reports for all the postseason games.
It was his second career touchdown catch. Tennessee went on to with 22-21.More news: Blake Griffin leveled on inadvertent elbow from JaVale McGee
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The Chiefs took a commanding 21-3 lead into halftime, but they failed to score the rest of the game.
The Chiefs had built a quick 14-0 lead in the first quarter, when quarterback Alex Smith used big completions to wide receiver Tyreek Hill and tight end Travis Kelce to set up touchdowns. The defense forced a stop, and kicker Harrison Butker hit the right upright on a 48-yard field goal attempt.
Just as important as firing up their run game will be stopping Kansas's City's dynamic backfield, which includes the NFL's top rusher in Kareem Hunt. Kelce was wobbly getting up, and ruled out for the game with a concussion.
The clock wound down and the Titans won their first playoff game since the 2003 season. The crowd went wild as fireworks popped over Arrowhead Stadium - until replays showed that Henry was down. The Jaguars locked up their first AFC South title when the Titans lost to the Rams.