Kansas City, Mo. — Josh Allen walked off the field inside Arrowhead Stadium a year ago juggling the disappointment of an AFC title game loss to the Chiefs with a profound sense of optimism about the future of his up-and-coming Buffalo Bills.

There was nothing but soul-crushing sorrow Sunday night.

Allen and Chiefs counterpart Patrick Mahomes had dueled all night in a playoff game sure to go down in history, leading their teams to a combined 25 points in the final 2 minutes of regulation. But it was Mahomes who delivered the coup de grace with a touchdown pass to Travis Kelce in overtime, lifting the Chiefs to a 42-36 victory.

The Chiefs were headed to their fourth straight AFC title game, this time against the Bengals next Sunday.

The Bills were headed back to Buffalo with a ninth straight playoff loss away from home.

“Pat played amazing. I’ve got a lot of respect for him and the Chiefs as a whole. They made one more play than we did; that’s what it came down to," Allen said. “But I’m proud of our guys, how we fought, how we battled, how we came through and persevered over some things throughout the course of this game and the course of the season. It obviously — it hurts.

"You don’t like feeling like this, especially back-to-back years at the same place.”

The way the game played out made it downright excruciating.

The Bills were trailing 23-14 in a heavyweight slugfest before finally mounting a second-half comeback, and Allen thought he'd finished it off when he found Gabriel Davis for the go-ahead score with just under 2 minutes left in regulation.

Surely, the league's top-ranked defense would hold on from there.

It turned out to be just the start of a chaotic finish: Mahomes threw a 64-yard touchdown pass to Tyreek Hill to regain the lead, Allen answered with a playoff-record fourth TD pass to Davis to give it back to Buffalo with 13 seconds to go, and the Chiefs somehow managed to give Harrison Butker a chance to kick a 49-yarder to send the game to overtime.

What was going through Allen's mind with 13 ticks on the clock?

“I'm thinking it's Pat Mahomes on the other side,” Allen replied.

The way the game played out, it seemed as if whatever team won the coin flip for overtime would win the game. And when Allen called tails, and the stadium lights shined on heads, the game was out of his hands.

Mahomes led his team swiftly down field, hit Kelce in the end zone and set off a wild celebration on the field.

“It's just going to leave a bad taste in our mouth,” said Davis, who had eight catches for 201 yards along with the four TDs. “I know that it'll be something I'll be thinking about until next season starts again, because there's still going to be games going on, and the Super Bowl's going to be played, and you're going to see it on TV and know you should have been in that position. So it's definitely going to have people with a chip on their shoulder.”

None more so than the one under center.

Allen was 27 of 37 for 329 yards passing and four touchdowns without an interception, and he led the Bills with 68 yards on the ground. No other player in NFL history had passed for at least 300 yards and three touchdowns, completed 70% of his throws and led his team with at least 65 yards rushing.

Except, well ... Mahomes did it, too.

“We've got to continue to work to beat him,” Bills coach Sean McDermott said. “Give him credit. He made a couple plays down the stretch and had a great game. That's what great players do: They make big plays in big moments of big games, and he made big plays. But again, I'm proud of the way the guys fought. They battled."

For a franchise that once lost four consecutive Super Bowls, it just wasn't enough.

Again.

“You're walking off the field and you realize you won't have the same roster each and every year, coaches included. A lot of us have been together five years. That might not be the case,” Bills safety Micah Hyde said. “It's beyond football. We're really like brothers. We celebrated, we cried together, we laughed together throughout the years. And once something like that happens, it's a hard way to go out. It's tough.”