It looked like the Buffalo Bills had blown another close game, and at Arrowhead Stadium of all places.

Then the other team made the mistake that cost them the game. That's a different role for the Bills.

The Kansas City Chiefs made the type of mistake the Bills have made in some of their close losses, and it opened the door for the Bills to escape with a 20-17 win that keeps their playoff dreams alive. A great touchdown in the final two minutes on a long lateral from Travis Kelce to Kadarius Toney was wiped out because Toney lined up barely offsides before the snap. The Bills held after that and won to improve to 7-6.

When the Chiefs (8-5) threw incomplete on fourth down, Mahomes was heated at the officials for the offsides call. It's unclear if he also was upset that officials missed that Buffalo's Von Miller was lined up offside on a third-and-15.

It was a bad defeat for the Chiefs in their race for the AFC's No. 1 seed.

The Bills finally caught a break. And did they ever need it.

Bills take an early lead

The Bills started the game looking like a team that understood it needed to start a winning streak or their playoff hopes would be close to finished.

James Cook scored a 25-yard touchdown on a pass from Josh Allen to give the Bills a 7-0 lead. The Bills scored again on a tough run by Allen in which he was hit at about the 5-yard line and then bulled forward through multiple defenders into the end zone for the score.

The Bills' defense played very well and the Chiefs were in danger of being shut out in the first half for the second time in Andy Reid's 101 home games with the Chiefs (the first was the 2018 season's AFC championship game against the New England Patriots).

The Chiefs finally broke through. Jerick McKinnon scored on a run before halftime. The Chiefs fell behind 17-7 but got a touchdown back from Rashee Rice. The Chiefs trailed just 17-14 after three quarters.

The Bills had to be worried. Just about every close game for them the past few years had gone against them, with some blown leads along the way like their Week 12 loss to the Philadelphia Eagles. The Bills couldn't afford another loss like that.

Game is tied in the 4th

The Chiefs went on a drive that ended with a field goal and the game was tied 17-17 with 11:31 to go. There were plenty of playoff implications on the line over the rest of the fourth quarter, with the Chiefs still in contention for the AFC's No. 1 seed and the 6-6 Bills hoping to remain in the playoff race.

The Bills had a bad series that ended when they punted on fourth-and-38. But the Chiefs couldn't do anything after that, another sign that this isn't a typical Chiefs offense. Kansas City is lacking the big plays and playmakers from years past, and the Chiefs especially missed injured running back Isiah Pacheco on Sunday.

Buffalo came up with the drive it needed after Kansas City punted. The Bills hit one 25-yard pass to Deonte Harty but the rest of the drive was short gains, and one important illegal contact penalty on Chiefs cornerback Jaylen Warren. The drive took a lot of time off the clock, but didn't end with a touchdown. The Chiefs got a third-down stop at the two-minute warning and the Bills settled for a field goal. They led 20-17 after that.

Bills fans couldn't have felt safe with that lead. Mahomes has a history of beating the Bills in the final minutes. Buffalo hasn't been good in close games under head coach Sean McDermott. There was a lot of time left for the Chiefs to at least tie it and maybe win it.

The Chiefs started with a couple of catches, including a big one from Rashee Rice to get Kansas City into Buffalo territory. The Chiefs had what looked like a touchdown on a great cross-field lateral from Kelce to Toney, but Toney was offsides to start the play and the Chiefs got penalized for it. The Chiefs didn't move the ball after that and the game was over.

The Chiefs were heated after the game. The Bills didn't care. They're happy to still have their season stay alive with a win, no matter how it came.