The Chiefs will not finish the season undefeated.

They lost for the first time since Christmas Day 2023, falling to the Bills 30-21 on Sunday. The Chiefs dropped to 9-1, while the Bills improved to 9-2 and within a half game of the best record in the AFC.

The Bills won the game, rather than the Chiefs losing it, when they decided to go for it on fourth-and-2 at the Kansas City 26 while leading by two points with 2:27 left. Josh Allen faked a quick throw left and then ran right, going untouched for a 26-yard touchdown as the Chiefs had no defender spying him.

It gave the Bills a two-score lead with 2:17 left.

The Chiefs had won an NFL-record nine games in a row after trailing by seven points or more, including the postseason. The Bills weren't about to let that happen Sunday, with Terrel Bernard picking Patrick Mahomes on fourth-and-13 with 1:07 left.

The 1972 Dolphins can celebrate being the last team to go undefeated as the Chiefs took their first loss since the Raiders beat them 338 days ago.

Allen went 27-of-40 for 262 yards with a touchdown and an interception. He ran for 55 yards and a touchdown on 12 carries. Khalil Shakir caught eight passes for 70 yards, and Curtis Samuel had five catches for 58 yards and a touchdown.

The Bills outgained the Chiefs 366 to 259.

Mahomes was 23-of-33 for 196 yards with three touchdowns and two interceptions. It was his 40th career game with at least three touchdown passes.

Xavier Worthy caught four passes for 61 yards and a touchdown, and tight end Noah Gray had two touchdowns on four catches for 23 yards. Kareem Hunt ran for 60 yards on 14 carries.