CHICAGO – Most of the Chicago Bears‘ offensive first half had consisted of zero points, an opening drive pick-six and a combined 3-of-12 passing from Mike Glennon and Mark Sanchez. Oh, the first-down chain broke at one point, more likely from rust than overuse.

Then late in the second quarter in an eventual 24-17 loss to Denver, in trotted Mitchell Trubisky, the second overall pick last spring, yet somehow the third-stringer for the preseason opener.

The less than capacity crowd at Soldier Field (16,978 unused tickets) rustled to life, out of curiosity, out of hope, out of a slumber that, after what it had just witnessed, forced it to deal with 0-16 nightmares.

Then Trubisky threw the ball, and it spiraled through the air like an actual NFL pass is supposed to spin. It was even caught. So was the next one and the next one and the next seven after that, by the way.

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When he scrambled out of the pocket, he did so on light feet that ran like actual NFL feet are supposed to run. Suddenly the Bears moved the ball like an actual NFL offense is supposed to move – forward, for first downs and eventually, just before half, into the end zone.

That was Trubisky to Victor Cruz, who did an abbreviated salsa dance, then realized it was preseason. He should have kept going. Everywhere else in Chicago they couldn’t stop dancing because the Bears might actually have themselves a quarterback.

“I thought it was fun,” Trubisky said. “It was kind of what I wanted to do.”

You could do worse than bet on Mitchell Trubisky being the season opening starter against Atlanta, the defending NFC champions. Coach John Fox tried to put a damper on that by declaring Glennon the starter in the second preseason game next week in Arizona.

“The depth chart is not going to change after one game, especially a preseason game,” Fox said.

Nice try, but by the time Trubisky finished with 18 of 25 (with a drop and two spikes) passing for 166 yards and a touchdown while gaining 38 more yards scrambling from potential sacks (“Who wants to get tackled?” he said), there was no containing the excitement here.

Scouts from other NFL clubs huddled by the elevators marveling at Trubisky’s balance, feet and arm. Teammates compared him to veteran stars in the league. And on the postgame radio show, at least one fan called in with suddenly high expectations for a Bears team that won three games last season.

“I see them going 12-4,” she said.

“Mike’s the starter,” Trubisky said, claiming he is comfortable on the third-string. “It’s his team. I was just able to get a lot of reps tonight. It’s the first preseason game … Hopefully we block everything out on the outside, what everyone is writing, what everyone is saying.”

You can’t fault everyone for getting excited here. There hasn’t been much to cheer for of late, especially in the tortuous days of Jay Cutler as quarterback. Glennon was signed for $18 million guaranteed, but he has been mostly a backup.

And Bears fans had been plenty skeptical of Trubisky. He started just one season in college at North Carolina and was hardly a household name. Yet Chicago made a bold trade, sending a third-rounder, a fourth-rounder and a 2018 third-rounder to San Francisco, to move up one measly spot in last spring’s draft. Many thought the Bears could have stayed put and got him anyway. Or they could have just taken Clemson’s Deshaun Watson.

Instead general manager Ryan Pace said they feared another team jumping in front of the Bears to get a quarterback they believed could lead this franchise.

“You can see why he was picked in the draft where he was picked in the draft,” Fox said.

Part of the euphoria was because Trubisky looked so good. Part of it is because the other guys looked so pedestrian.

Glennon went 2-for-8 for 20 yards. The offense went nowhere. His passes weren’t crisp. Yes, that was the first strong Denver defense across the way, but still. Then there was that terrible toss on the interception on the first drive of the preseason that was taken back the other way. “The ball just got away from me,” Glennon said. “I just didn’t play well tonight.”

Sanchez was 1-for-4 for 4 yards, getting limited time because, Fox said, as a veteran he’s had plenty of experience. He’s a backup and nothing more. When the opportunity to run a two-minute offense arose, Trubisky went right in.

Trubisky made a point to savor the milestone. Sure it was the preseason, but since he was 5 years old growing up in suburban Cleveland he dreamed of, and worked toward, becoming an NFL quarterback. Now here he was.

“It was important for me to not just let this moment go by,” Trubisky said. “Soaking it in, especially at Soldier Field … Hopefully it’s the first game in a long journey.

“It’s like a dream come true.”

One preseason game won’t shuffle Fox’s depth chart here, won’t unseat Glennon as the starter. It will ignite a desperately hopeful fan base, newspaper columns and radio call-in shows though.

Not every game will go like this, but with that arm and those feet, the Mitchell Trubisky Era is inevitable, probably sooner than anyone expected.