For a moment on Sunday, the Kansas City Chiefs had a go-ahead score for the ages in a critical AFC matchup against the Buffalo Bills.

But a critical penalty wiped it out it in an eventual 20-17 Bills win.

With Kansas City trailing 20-17 in the final two minutes of regulation, Patrick Mahomes hit a wide open Travis Kelce over the middle of the field on second-and-10 from the Buffalo 49-yard line.

Kelce ran toward the end zone from the 30-yard line, then spotted Kadarius Toney standing by himself near the left sideline. He lateraled the ball to Toney, who ran untouched into the end zone for what looked like a thrilling go-ahead touchdown in front of a frantic Kansas City crowd.

The lateral did not appear to be designed. Instead, Kelce appeared to see an opportunity and improvised. One of the game's most exciting players helped secure what looked like one of the most exciting touchdowns of this or any season.

But a flag was thrown at the line of scrimmage just after the snap. Toney lined up with his right foot in the neutral zone. He was called offside and the play was nullified.

Instead of scoring a touchdown for a 24-20 lead, the Chiefs were penalized 5 yards to set up second-and-15. They ended up turning the ball over on downs after failing to gain another yard, and the Bills secured a critical win.

With the victory, the Bills improved to 7-6 to keep their dwindling playoff hopes alive. The Chiefs, meanwhile, fell to 8-5, putting them two games behind the 10-3 Baltimore Ravens and their hopes of securing home-field advantage in the playoffs further in peril. The 9-3 Miami Dolphins have a chance to tie the Ravens on Monday against the Tennessee Titans.

Mahomes, Andy Reid not happy with the call

After the game, Mahomes was livid with the official who made the call and let him know.

Mahomes told reporters postgame that he asked three officials for an explanation without receiving one. He then criticized the officials for taking "away greatness."

"It's obviously tough to swallow, not only for me, just for football in general," Mahomes said. "To take away greatness like that. For a guy like Travis to make a play like that.

"I know as fans, you want to see the guys on the field decide the game. ... They're human, man. They make mistakes. But it's every week we're talking about something."

Mahomes was then asked what specifically about the call "made him boil over."

"It's the call, man," Mahomes said. "Just in that moment. ... In that moment — I've played seven years and never had offensive offside called. ... It doesn't get called. And if it does, they warn you. There was no warning throughout the entire game. And you wait til there's a minute left to make a call like that. It's tough, man."

Referee explains call

Referee Carl Cheffers explained why the call was made in a pool report.

“It’s one of those things we don’t want to be overly technical on, but when in his alignment he’s lined up over the ball, that’s something that we are going to call as offensive offside,” Cheffers told pool reporter Matt Derrick.

Chiefs head coach Andy Reid likewise expressed his dissatisfaction with the call while speaking with reporters.

“Normally I get a warning before that’s called,” Reid said, per the Kansas City Star's Sam McDowell. "A bit embarrassing for the National Football League for that to take place.”

Cheffers said that officials are willing to advise players on their alignment when they seek it and that Toney's alignment was too egregious to overlook.

“Ultimately, if they look for alignment advice, certainly we are going to give it to them," Cheffers continued. But ultimately they are responsible for wherever they line up. And certainly no warning is required, especially if they are lined up so far offside where they’re actually blocking our view of the ball.

"So we would give them some sort of warning if it was anywhere close, but this particular one is beyond a warning.”