Trubisky vs. Glennon: What to watch in Bears' third preseason game

It’s Mike Glennon vs. Mitch Trubisky.

The prize? The Bears’ starting quarterback job.

Yep, Sunday is absolutely more than your typical third preseason game. It isn’t simply a dress rehearsal against the Titans in Nashville, Tennessee.

Glennon is playing for the starting job he once was promised, and Trubisky is playing to take it.

Here is what we’ll be watching:

Mike must excel

The Bears still see immense benefits in taking a patient approach to Trubisky’s development, but it’s a plan that requires Glennon to be better than he has been since training camp opened.

Uneven, turnover-prone play won’t work. Glennon must be efficient. It would help if he could hit receivers in stride more often, too.

That said, an average performance by Glennon might be all it takes to keep Trubisky on the sideline when the regular season opens. The question is whether he’s capable of producing it.

It’s not too late for Glennon to redeem himself, but it is late. This is arguably his last chance to prove this season truly is his.

Trubisky is playing with the starters because of his quick development but also because of Glennon’s alarmingly uninspired play. Two horrible interceptions, a third one that was dropped and a 48.4 passer rating highlight Glennon’s woes.

‘‘The competitor in him is going to bring out a little bit more,’’ tight end Zach Miller said of Glennon. ‘‘I think he’s confident in his ability.’’

Still, it’s not a good sign when Glennon’s resolve and confidence have become a storyline — and they have been for weeks.

More for Mitch

Coach John Fox thought Trubisky played well with the starters in practice. He said the Bears’ plan for him in the second half against the Titans will be based on play counts and didn’t rule out inserting him earlier.

‘‘We’ll just see how it goes,’’ Fox said.

Testing Trubisky extends beyond the players he plays with and against on the field. It involves a variety of play calls from offensive coordinator Dowell Loggains, who has installed a game plan. If Trubisky is as comfortable with everything as his teammates say he is, it’s time to test it.

Trubisky has had success from the shotgun and on bootlegs this preseason. Because of it, he has opened eyes across the league. But more standard under-center drops of three, five or seven steps might be coming against the Titans.

‘‘We’re excited [with] where he’s at right now,’’ cornerback Prince Amukamara said. ‘‘You want guys to be playing confident this time around, and we’re excited to see him play.’’

If Trubisky instantly connects with receiver Kevin White, that might spell the end for Glennon.

Manhandling Mariota

The strong play of the Bears’ No. 1 defense last week against the Cardinals is a reason for optimism. It included limiting All-Pro running back David Johnson to three yards on three carries.

The Cardinals’ starters only found the end zone after taking over on the Bears’ 43-yard line in the wake of safety Tyrann Mathieu’s long return after an interception of Glennon.

Now comes Marcus Mariota, the quarterback Bears general manager Ryan Pace coveted in the draft two years ago. Mariota, who hasn’t thrown an interception in the red zone in two seasons, is the leader of a young Titans team that is expected to make a major leap this season.

The Bears’ defense is a blend of young, homegrown talent and capable veterans with a lot to prove. They think they’ve established an identity.

Amukamara said they want to be ‘‘feared.’’ Defensive end Akiem Hicks said they want to be ‘‘nasty.’’

‘‘We knew where we wanted to be,’’ Hicks said. ‘‘We knew what our culture and what our identity wanted to be. Now we’re just implementing it.’’

Not a Long line

At this point, it will be surprising if guard Kyle Long is ready for the regular-season opener. His recovery from ankle surgery in December has become long and arduous.

Fox sounded particularly ominous Friday.

‘‘When he’s back to close to himself, he’ll be back in there,’’ Fox said. ‘‘I can’t honestly say when that’s going to be.’’

But Hroniss Grasu has stabilized the interior of the offensive line. After missing all of last season with a torn anterior cruciate ligament in his right knee, Grasu is starting to resemble the center the Bears thought he would be when they drafted him in the third round in 2015. His improvement has allowed Cody Whitehair to shift to left guard in Long’s absence.

Behind an offensive line of Grasu, Whitehair, right guard Josh Sitton and tackles Bobby Massie and Charles Leno Jr., rookie running back Tarik Cohen ran for 77 yards on 11 carries last week against the Cardinals.

Time to shine

There are a number of players to watch when it comes to the Bears’ final cuts.

Is cornerback Kyle Fuller’s strong recent play an indication of good things to come this season?

Do the Bears keep promising young receiver Tanner Gentry or savvy veteran Victor Cruz? How about Roy Robertson-Harris or Mitch Unrein on the defensive line?

Is Daniel Brown or Ben Braunecker talented enough to warrant keeping four tight ends?

Who has more value on special teams, receiver Deonte Thompson or running back Benny Cunningham? What about receiver Josh Bellamy?

The Bears will have better answers after Sunday.

Follow me on Twitter @adamjahns.

Email: ajahns@suntimes.com

Trubisky vs. Glennon: What to watch in Bears’ third preseason game