KANSAS CITY, Mo. >> Jay Cutler and the Chicago Bears made a bad day even worse for the Kansas City Chiefs.

Cutler led the Bears to a pair of fourth-quarter touchdowns Sunday, the second an alert toss to Matt Forte with 18 seconds left, giving them an 18-17 comeback victory after Kansas City lost star running back Jamaal Charles to a potentially season-ending knee injury.

Chicago (2-3) trailed 17-3 early in the third quarter when Charles went down while trying to make a cut. The preliminary diagnosis was a torn ACL and Charles will have an MRI exam Monday.

The Bears quickly seized the momentum.

After Robbie Gould’s second field goal got them going, Cutler led an 88-yard drive that he capped with a 22-yard strike to Marquess Wilson with 3:05 left. The 2-point conversion came up short, but the Bears defense responded by forcing a quick three-and-out.

With help from a pass interference call on Chiefs rookie Marcus Peters, the Bears quickly moved down the field. That’s when Cutler took a snap from the shotgun, dropped the ball, picked it up and spotted Forte running past safety Husain Abdullah in the end zone for the go-ahead score.

The Chiefs (1-4) tried a 66-yard field goal that came up short as time expired.

It was the second heartbreaking defeat at home for Kansas City this season. AFC West rival Denver scored two touchdowns in the final 2:27 for a 31-24 victory last month.

Making this one even worse was the injury to Charles, who was starting to get into a rhythm went he went down deep in Chicago territory. He immediately grabbed his right knee — Charles tore the ACL in his left knee in 2012 — and was helped straight to the locker room.

“It looks more like a torn ACL than anything else,” Chiefs coach Andy Reid said. “We’ll have an MRI on it tomorrow and we’ll just see how that goes.”

That drive stalled, and Cairo Santos had his field-goal attempt blocked. The missed points wound up looming large in a game that Kansas City will remember for its missed opportunities.

“The bottom line of the game is we have to make plays,” Reid said. “The play-callers and/or the players, we have to do a better job there given the opportunities.”

Until Charles went down, everything was going splendidly for the Chiefs, who had jumped out to a comfortable lead thanks to a pair of surprising touchdowns.

The first occurred on the third series of the game, when Cutler was sacked in the end zone by Jaye Howard and Allen Bailey. Cutler lost the ball before hitting the turf, and rookie linebacker Ramik Wilson jumped on it for a touchdown in his first NFL start.

The Chiefs’ second TD came when Alex Smith connected with DeAnthony Thomas with a 14-yard pitch-and-catch midway through the second quarter. Why so surprising? It was just the second scoring reception by a Kansas City wide receiver since December 2013.

Meanwhile, the Bears struggled through injury problems of their own.

Wide receivers Alshon Jeffery and Eddie Royal were both out, along with three of the Bears’ starting offensive linemen. The result was a tough afternoon for Cutler until the final few minutes, when he made the plays that mattered most.