By Chris Emma—

CHICAGO (CBS) – Chants filled the upper reaches of Soldier Field on Thursday evening, the kind not often heard in a preseason game.

Mitch Tru-bis-ky! Mitch Tru-bis-ky!

There was a buzz in the air along the lakefront as the Bears took the field for their first of four preseason games. The final score, 24-17 in favor of the Broncos, seemed inconsequential after what rookie quarterback Mitchell Trubisky showed — hope for a franchise long searching.

Trubisky completed 18 of 25 passes for 166 yards and a touchdown in his professional debut, leading the Bears to points on three of his five series at quarterback. More importantly, he commanded the offense with poise and managed difficult situations throughout the night.

For the better part of two decades, Bears fans have clamored for the backup quarterback. They should certainly be excited about this one.

“He played really well, there’s no doubt about that,” starter Mike Glennon said of Trubisky.

The game didn’t go well for Glennon, the 27-year-old given a second chance to be an NFL starter. He threw a pick-six on the first series of this game — a pass into triple coverage that found the hands of three-time Pro Bowl cornerback Chris Harris Jr. — then followed through with more troubles. Glennon later had receiver Cameron Meredith open on a “Go” route and undershot him, missing several times on his throws.

Glennon finished the game 2-of-8 for 20 yards, with his drives finishing with a pick-six, punt, fumble and punt.

Coach John Fox said after the game that he wouldn’t rearrange the depth chart after one preseason game, meaning Glennon is still the starter and Trubisky is still the project. But Thursday night at Soldier Field offered a good glimpse at a quarterback quandary that won’t go away if these trends continue.

“Mike’s the starter,” Trubisky said with no hesitation. “This is his team.”

The successes of Trubisky came in an offense structured to his strengths but also pressed against in-game challenges. Bears offensive coordinator Dowell Loggains used Trubisky’s mobility in play-calling by bringing him outside the pocket quite often. He responded well, displaying the ability to throw the ball with poise and accuracy while on the move.

Trubisky provided an initial confirmation of all the belief in his natural abilities — the mobility, arm strength and accuracy. He also displayed the kind of command that these Bears had hoped. It was just one preseason game, but those at Soldier Field got to see a rookie quarterback who appears more ready than even his coaches could’ve anticipated.

Trubisky entered with 1:55 on the clock for the first half and ran the two-minute drill. He went 4-of-4 for 24 yards and led the Bears 50 yards down the field for a touchdown, a two-yard strike to Victor Cruz in the flat. After bringing the Bears back from an early 10-0 deficit, he managed the game well by utilizing the ground game to maintain a 17-10 lead, all while showing confidence in the huddle.

All that was missing was the game-winning drive, with the Bears going from their own 25-yard line to the Broncos’ 22 before the clock ran to zeroes. Trubisky spoke of disappointment after a loss, but the Bears fell because of holes in their third-string defense. This wasn’t the fault of Trubisky, who has every right to be pleased with his performance.

“It was kind of what I wanted to do,” Trubisky said. “Go out there, just be consistent, move the ball with the offense, show command in the huddle, at the line of scrimmage.

“It was a good start, and we have a long way to go.”

One month from the season opener at Soldier Field, it will be fascinating to see where this does go.

Glennon did no part to quiet the talks of a quarterback competition. While the Bears wanted to see Trubisky show command of an offense, they hoped Glennon could lead the starting unit with his abilities. Instead, Glennon had little accuracy in his arm and didn’t look like the man tasked with bringing this team to contention. This came in a system from Loggains that was intentionally bland but also suited for Glennon to work primarily with quick decisions in the pocket. They played it to his strengths and got little in return.

The Bears signed Glennon to a three-year, $45-million deal, of which $18.5 million is guaranteed. While the team has stated that he’s not just a bridge quarterback, the contract indicates otherwise. Now, it’s already worth wondering how many starts he makes this season.

After all, Glennon entered training camp carrying the hopes for 2017 on his shoulders. Ideally, he could buy time for Trubisky’s development and ensure the prized prospect isn’t rushed.

But what if Trubisky is indeed ready for action? He sure looked so after one preseason game. Could he steal that starting spot from Glennon after four strong exhibitions? Three?

Fox wasn’t prepared to open up that can of worms before the media. Glennon has been ready for it.

“When you take a guy that high (in the draft), I immediately knew that there could be something stirred up,” Glennon said. “I’m not going to focus on the outside world.

“I wouldn’t say my phone’s going to be off, but if you work for NFL Network, I’m not going to be checking you out.”

Bears general manager Ryan Pace made the bold move up for Trubisky because of his convictions that this would be the leader of better days for the franchise. Pace said that he wanted to be “great” and that drafting a quarterback of Trubisky’s caliber would bring the Bears to said greatness.

Pace, Fox and this Bears brass entered the preseason hoping that firm structure at the quarterback position would eliminate any thought to a competition for the starting job. Mike is the starter, they’ve said over and over again since the surprise on draft night, and Mitch is the future, or so they’ve planned.

Hope arrived sooner than the Bears could’ve imagined.

Chris Emma covers the Bears, Chicago’s sports scene and more for Follow him on Twitter @CEmma670 and like his Facebook page.