Inside a downcast home locker room at Soldier Field, Chicago Bears quarterback Justin Fields lay down inside his stall, full uniform still on and the wheels in his brain spinning in all directions. Fields couldn’t really comprehend how such a fun and positive afternoon had turned so dreadful, how his most productive outing as an NFL quarterback had been punctuated by two late turnovers, how a 21-point Bears lead had unraveled and somehow become a gutting three-point home loss.

How on earth did Sunday’s game go into the books as a 31-28 Denver Broncos victory?

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“Yeah,” Fields said. “It hurt. Just the lead that we had. And we weren’t able to finish it off. I wasn’t able to finish it off.

“Of course, it hurt. It’s almost like … Ah. I don’t know. I don’t know. It’s just … Yeah. The emotions are going everywhere.”

Somehow it made all the sense in the world.

It’s almost like … Ah. I don’t know. I don’t know. It’s just … Yeah.

When will all this confusion and hurt go away?

On a picturesque October afternoon by Lake Michigan, Fields and the Bears provided much-needed feel-good for the better part of three quarters. It felt like a significant moment, a seized opportunity against a floundering opponent, the long-awaited breakthrough to snap a 13-game losing skid.

When Fields threw his fourth touchdown pass — a nifty ad-libbed 2-yard bullet to running back Khalil Herbert — the Bears had a 28-7 lead with 4:11 remaining in the third quarter and their quarterback had only one incompletion on his first 24 attempts.

It was surgical.

“We were in a rhythm,” Fields said. “Luke (Getsy) was dialing it up. The guys were protecting up front and the receivers were getting open.”

Felt like a clinic.

“You saw rhythm. You saw timing. You saw the receivers were in phase with everybody,” coach Matt Eberflus said. “There was just really good flow.”

Man oh man, were the Bears in position to let it all out, to unleash 11 months of frustration for a blowout victory that could soothe a city for at least a couple of days.

Until the collapse began. The meltdown. The evaporation of a massive lead with the Bears losing a game they led by 21 points or more for the first time since 2002 when a Dick Jauron-led team let a 27-6 lead over Tom Brady and the New England Patriots slip away in Champaign, Ill.

That wasn’t the history the Bears were hoping to make in a game where Fields set a new franchise record by completing 16 consecutive passes in the first half.

His final numbers: 28-for-35 for a career-high 335 yards and a career-high four touchdown passes. Fields’ highlight reel began with a 29-yard scoring bomb to DJ Moore in the second quarter and later included a pair of TD strikes to Kmet.

“You can feel it when you get in that kind of groove,” Kmet said. “Even just the simple things. We were hitting little stop routes and they were turning into 8- or 9-yard gains That’s what keeps drives going. We were really efficient today.”

And yet …

With these Bears, there always seems to be that unfathomable, stomach-turning twist.

So of course, Russell Wilson and the Broncos responded with two way-too-easy touchdown drives to make it a one-score game with 9:36 left. And of course on the ensuing Bears possession, on a first down play from the Broncos 48 yard line, Fields carried out his fake on a play-action bootleg pass, then turned around to find Broncos outside linebacker Nik Bonitto in his kitchen.

Fields had a split-second to react, to figure out something to do, to apply the rule on naked bootlegs and try to avoid a sack at all costs.

“I was trying to dirt the ball,” he said. “It didn’t end up working that way.”

Fields’ attempt to throw the football away was thwarted by Bonitto’s big hit. The ball squirted free and bounced once before Jonathon Cooper scooped it and raced 35 yards for a game-tying score.

“He either has to dirt the ball or get (himself) to what he feels is the best way to get rid of it,” Eberflus said.

Added Fields: “I don’t know if I could really do anything on that one, to be honest with you.”

On the next drive? With an opportunity to still drive down and win the game? The Bears marched into the red zone with time running down. They had less than a yard to get on fourth down from the Denver 18 with 2:57 left.

Rather than settle for a 36-yard Cairo Santos field goal attempt and a 31-28 lead, they called a read-option run.

“If we get it, the game’s over most likely,” Fields said. “… I loved the decision. It shows coach has trust in us to convert on that and in that situation.”

But of course, the Bears missed a block on the backside. Of course, Herbert was stuffed for no gain. Of course, the Broncos converted that turnover on downs into a go-ahead 48-yard field goal drive. And of course, the Bears’ final possession ended with another accident, another malfunction, another fourth-quarter Fields interception — his third this year and ninth in the last two seasons.

That came on third-and-13 from the Bears 48, two snaps after Fields was penalized for intentional grounding. Fields’ final pass was delivered with crossed wires.

Against a man coverage look, Fields was hoping Kmet would see the depth of Broncos safety Kareem Jackson, improvise on his route, run to a spot and sit down. That’s where Fields threw the football. But Kmet identified what he thought was a man-match coverage and whipped his route.

Jackson raced in and swiped the pass.

Turnover. Game over.

“All in all it’s my fault,” Fields said. “Against man coverage, (Cole) is supposed to do what he did. I wanted him to just play football and kind of sit down in space. That’s why I threw it to a spot how I did. It was really a miscommunication.”

Added Kmet: “We’re both beating ourselves up over that for sure. It’s just something where we both have to be on the same page.”

It was an unfortunate miscue in a big moment, another late-game breakdown by a team that has spent far too much of the past two seasons losing games they maybe could have, would have, should have won.

For so much of Sunday, the Bears looked like they were making positive strides and showing encouraging playmaking ability. They seemed ready to break their 342-day drought without a win in convincing fashion.

Led by Fields, they had undeniable momentum.

They were rolling. They were set. Somehow, they lost.

It’s almost like … I don’t know. It’s just. Yeah.