WATCH: "Be the Grim Reaper" - Andy Reid shares advice he gave Patrick Mahomes to pull off insane 13-second FG drive 

Patrick Mahomes is simply unbelievable. His heroics last night led the Kansas City Chiefs to a 42-36 overtime victory over Josh Allen and the Buffalo Bills to advance to next weekend's AFC Championship game.

With just 13 seconds left in the game, the Chiefs were down by three points, needing a field goal to level matters and send the contest to overtime. For reasons unknown, the Bills elected to kick the ball long instead of opting for a squib kick which would have taken time away from Mahomes.

And within those 13 seconds, he delivered two passes for 44 yards, setting up a 49-yard field goal that kicker Harrison Butker successfully put through the uprights.

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WATCH: Andy Reid provides the spark that led the Chiefs to defeat the Bills

Speaking to the media after the game, head coach Andy Reid revealed what he said to his quarterback before the Chiefs' late field goal drive. Simply stating:

"When it's grim be the Grim Reaper.

Andy Reid went on to heap praise on his superstar quarterback and lauded his ability to make his teammates better.

"He made everyone around him better which he is great at and he just does it effortlessly. When it gets tough, he's gonna be there battling and the players appreciate that."

Mahomes leads Chiefs to the AFC Championship game

AFC Divisional Playoffs - Buffalo Bills v Kansas City Chiefs

With what is set to become the NFL's newest quarterback rivalry, Mahomes and Allen showed up and showed out for Sunday night's AFC Divisional Round matchup at Arrowhead Stadium.

The two combined for a total of 707 passing yards, 137 yards rushing and eight total touchdowns. They both also overtook Hall of Fame quarterback Bart Starr's NFL record for career playoff passer rating, too. Mahomes leads the league with 107.2 with Allen a close second with 106.6 in the post-season.

It was a simply stellar performance from a pair of phenomenal young quarterbacks and it was just unfortunate that one of them had to lose, but lose it they did in gut-wrenching circumstances.

After losing the overtime coin toss, Allen and the offense had to sit back and see if the number one ranked defense in the regular season could prevent the Chiefs from ending the game with a touchdown.

The Bills offense would not step foot on the field again as Mahomes marched 75 yards in eight plays, culminating in an eight-yard touchdown pass to Travis Kelce to seal the victory.

As the Bills head home thinking about what might have been, the Chiefs welcome the Cincinnati Bengals to Arrowhead for the AFC Championship game next Sunday night for a place in the Super Bowl.