The NFL is a results-driven business. And when the final gun sounded at the end of Sunday's thriller between the Kansas City Chiefs and Cleveland Browns, the defending Super Bowl champions had escaped with a 22-17 win that propelled them into the AFC Championship Game for the third consecutive season.

But while the Chiefs have now won 11 of 12 and are the first team in AFC history to host the conference title tilt in three straight seasons, this game wound up following a somewhat disquietingly similar script. Dating all the way back to a 35-9 throttling of the hapless New York Jets in Week 8, the Chiefs haven't beaten a team by more than six points since Nov. 1.

They may have sported the league's best regular-season record at 14-2. They may be the defending Super Bowl champions. And depending on the health of quarterback Patrick Mahomes, they will likely be favored by Vegas oddsmakers next week.

But heading into a matchup with a Buffalo Bills team that is just as hot in terms of wins and losses, Kansas City doesn't look the part of an unstoppable juggernaut. It looks like a word that hasn't been associated with the franchise in quite some time: vulnerable.

It didn't look like that was going to be the case in the first half Sunday, though.

Playing against a Cleveland defense that has struggled mightily at times, Kansas City moved the ball at will. The Chiefs amassed almost 300 yards of offense in the first half. The run game was working. Mahomes and the passing attack were sharp. The defense played well and got a huge turnover near the end of the second quarter. A missed extra point was about all that went wrong, and the Chiefs were up 16 at the intermission.

When safety Tyrann Mathieu picked off Cleveland quarterback Baker Mayfield deep in Browns territory on the first series of the second half, it looked like the rout was on.

But Kansas City's next drive culminated in another missed kick by Harrison Butker. The Browns then drove the length of the field, marching 77 yards in eight plays to close the score to 19-10.

The Chiefs were able to stretch the lead to 12 on their next possession, but it came at a price: the injury that will dominate the conversation around next week's game for the next several days.

While trying to avoid the pass rush, Mahomes (who had already suffered what appeared to be a toe injury in the first half) was hauled to the ground after a throw. He hit his head, was noticeably wobbly afterward and was escorted off the field and into the locker room.

He would not return.

Now, before anyone starts panicking prematurely, head coach Andy Reid sounded optimistic after the game that Mahomes will be back out there next Sunday against Buffalo.

"He got hit in the back of the head and kind of knocked the wind out of him," Reid said. "... He's doing great right now, which is a real positive, passed all the deals that he needed to pass, so we'll see where it goes from here. ... I just talked to him. He's doing good. We'll see how he is tomorrow, but right now he's feeling good."

It's also worth noting the Chiefs rallied around their fallen signal-caller.

Backup quarterback Chad Henne threw an ugly interception, but he also made a handful of plays with his arm—including a fourth-down throw to Tyreek Hill that salted the game away. Kansas City's defense struggled much of the second half but made plays late when it needed to.

Mathieu talked up the latter while speaking to CBS Sports after the game.

"We're one team," he said. "We're one heartbeat. We play for one another, and that's really all it's about. I think any time any of our teammates go down, we always feel the need to kind of step it up a notch and take care of what we need to take care of."

Assuming for a moment that Reid is correct and Mahomes is able to go again next week against Buffalo, no one is saying to hit the big red panic button.

This was a game in which the Chiefs piled up 438 yards of offense even with Mahomes out almost half the afternoon. Both Travis Kelce and Hill had over 100 receiving yards. Kansas City had 123 rushing yards and averaged 5.1 yards per pop while allowing just 308 yards of total offense to the Browns.

The AFC title game could also feature the potential return of rookie running back Clyde Edwards-Helaire, who gashed the Bills for 161 yards on 26 carries during a nine-point Chiefs win in Week 6.

But as has been the case for the past two-plus months, the Chiefs weren't able to put the Browns away until the very end. Most of those 308 yards allowed came after the intermission.

Next week's opponent isn't a one-dimensional team with a defense that couldn't cover a bed with a sheet. The only team in the league that averaged more yards per game during the regular season was the Chiefs. Buffalo was actually more prolific than Mahomes and Kansas City in the scoring department, averaging 31.3 points per game to 29.6.

And while the Bills defense won't be confused with the 1985 Chicago Bears any time soon, it was a respectable 14th in yards allowed and 16th in points allowed. Never mind the fantastic outing by said defense in Saturday's two-score win over the Baltimore Ravens—a game in which Buffalo's defense outscored Baltimore's offense.

The mantra of any NFL team in the playoffs is all of three words long: survive and advance. The Chiefs did just that Sunday, overcoming quite a bit of adversity in the process. And until someone knocks them off, they remain the king of the hill in the NFL.

But momentum is also very much a thing in this league, and it's difficult to get rolling when every week's game is a close scrape.

Had the Chiefs blown out a frankly overmatched Browns team Sunday, they could have taken back the title of the AFC's hottest squad ahead of their biggest game of the season. Instead, they pulled out yet another close one and added at least one massive question swirling above them in the process.

And while Kansas City fans have every reason to be relieved after Sunday's squeaker, there's also some cause for concern.

This would be the absolute worst time of the season to finally cut one too close.