On Sunday morning, as betting action on the NFL heated up, sportsbooks around the nation pointed to the Chiefs as the team that could do the most damage to the bookmakers' bottom line.
Kansas City opened as a 4-point favorite over the Titans earlier last week. When quarterback Patrick Mahomes was cleared to play, the line grew to as high as Kansas City -6.5, and bets poured in on the Chiefs.
Two hours before kickoff, more than 97% of the money bet on the game's point spread was on Kansas City at Caesars Sportsbook in Nevada. FanDuel, which operates primarily on the East Coast, reported more than 95% of the money at their sportsbook was on the Chiefs.
It was the biggest decision of the early kickoffs for many sportsbooks, and it ended in stunning fashion.
Leading 32-27 late in the fourth quarter, Kansas City got a fourth-down stop and took over at the Tennessee 32-yard line with 1:55 to play. The Chiefs ran three plays and lined up for a 46-yard field goal that would have put them up eight, enough to cover the spread. According to ESPN Stats and Information data, Kansas City's win probability, at that point, was over 99%, and bettors appeared to be poised to win big.
However, the snap on the field-goal attempt caught Chiefs holder Dustin Colquitt off guard and ultimately resulted in an intentional grounding penalty on Kansas City, giving the ball back to the Titans on their 39-yard line with 1:21 to play.
Four plays later, Tennessee quarterback Ryan Tannehill threw a 23-yard touchdown pass to Adam Humphries. The Titans completed a two-point conversion and led 35-32 with 23 seconds remaining. The craziness wasn't over, yet.
On Kansas City's ensuing possession, Mahomes quickly drove the Chiefs into field goal range, only for Harrison Butker's potential game-tying 52-yard field goal to get blocked by Joshua Kalu, who, replays showed, was close to being offside.
The end result -- the Titans winning 35-32 -- was met with groans from the majority of bettors. Caesars Sportsbook estimated Tennessee's comeback produced a mid-six-figure swing in favor of the house. Las Vegas sportsbook operator CG Technology, and New Jersey sportsbook PointsBet experienced similar swings in their favor.
Nationwide, bookmakers estimated, easily more than $10 million shifted on the game.
"While it's a bit difficult to exactly pinpoint the swing, as a great deal of our liability on that game was tied up in parlays, we can confidently say that it was close to a half a million dollars," Patrick Eichner of sportsbook PointsBet told ESPN.
Not every bettor was unhappy with the Titans' win, which, according to their win probability, was the largest comeback of the season. A big bettor in New Jersey placed a $440,000 bet on the Titans +6 with bookmaker William Hill.
ESPN's Ben Fawkes contributed reporting to this story.