INDIANAPOLIS – The defensive side of the ball in Indianapolis includes 30-somethings in Robert Mathis, Mike Adams, D'Qwell Jackson and Kendall Langford.

Combined, those four have strapped it up to play in 610 career NFL games.

Their experience is vast.

So when Chuck Pagano says a rookie on defense is one of the "brightest guys on that side of the football" you take note.

Yep, that's Antonio Morrison.

"You would never know if you listened to him communicate in the building and on the sideline and at practice that this guy is a first-year player – he's a rookie," Chuck Pagano says of the fourth-round pick out of Florida.

"He seems like he's been here four, five or six years. He has all the Colt traits that you want, he is a really good football player and he's tough and nasty and we love guys that run and hit. He loves contact, a lot."

Bottle that description up and it's what makes a coach salivate when trying to seek out specific characteristics in a football player, particularly a middle linebacker.

Those qualities could be on display Sunday in a major, major way.

Morrison is a candidate, perhaps the lead one, to start next to D'Qwell Jackson in the 2016 season opener.

With Sio Moore (hamstring) still sidelined, and Nate Irving no longer in Indy, the Colts need a starter next to Jackson.

Even though Morrison and Jackson have had very limited reps beside each other this offseason, the vet sees what Pagano sees.

"He's definitely one of the higher IQ, smarter football guys on this team," Jackson says of Morrison.

"He's a football guy. You can tell he works at it when he's away from this building. With a guy like that, you see why. He's passionate about it and he takes the time to learn it. And it means something to him."

Back during the offseason program, a starting role for Morrison seemed like a long shot.

A hamstring injury on the first day of rookie minicamp sidelined him for the entire offseason program.

The Colts have always gushed about Morrison, but missing valuable OTA/minicamp time leads to a steep climb for any rookie.

But the Colts knew Morrison wasn't your typical rookie, given how he finished his senior season at the University of Florida.

During this year's NFL Draft, the Colts traded back nine spots in the second round.

In exchange, they received the Green Bay Packers second and fourth-round picks.

At No. 59, they took safety T.J. Green.

At No. 125, the pick was inside linebacker Antonio Morrison.

Will both of them be starting on Sunday?