When Tanzel Smart was selected in the sixth round of the NFL draft a few months ago, there likely weren't many who envisioned him lining up alongside the starting defense on Sept. 10.

But given Aaron Donald's absence as the team and his representation continue to negotiate a contract extension, that's exactly what may happen on Sunday against the Colts.

Smart has steadily improved since arriving for rookie minicamp, showing an ability to be disruptive in the middle of a talented front seven.

"I think Tanzel is one of those players that he's a natural fit for anything, because all he does is exactly what you want him to do and he continues to get better every single day," head coach Sean McVay said this week, giving credit to D-line coach Bill Johnson and defensive quality control coach Thad Bogardus for Smart's development. "[Y]ou see [on film], 'Hey, there's Smart again showing up doing exactly what he's supposed to do — making a play, affecting the offense.'

"Everybody wants to probably make a point about that he's short" — Smart is listed at 6-foot-1 — "but he seems to be a guy who tips the ball as much as anybody," McVay continued. "You feel him as an offensive coach. Can't say enough about how please we've been with what Tanzel's done."

Defensive coordinator Wade Phillips echoed the praise.

"Tanzel Smart's come in and done a really good job as a rookie," Phillips said Thursday. "Lower-round draft choice, we thought he had some ability and he's shown that ability. So he's going to have to play in the rotation, and we think he'll play alright. He played well in the preseason. And I think he's still got to get better, but I think he will."

For his part, Smart said he feels like he's progressed well in the defense but added, "I've still got a lot of work to do. Just getting more in the playbook — you've got to get into the playbook with this defense. It's simple, but you can mess it up real fast."

That said, he doesn't feel like what he's being asked to do in the pros is all that different from college.

"It's the same concepts and the same techniques," Smart said. "So it's really pretty much the same, just a different name of it."

Smart's teammates have taken notice of his work ethic and how he's improved. Entering his sixth year, Michael Brockers complimented Smart's high motor.

"He doesn't stop. He's always doing extra work," Brockers said. "He's doing [work] after meetings, after workouts. When you want to look up a rookie [in the dictionary] and see a good rookie, his picture should be in there."

Brockers went on to call Smart aggressive, young, and hungry.

"And I think that's the most important thing about it — how hungry he is," Brockers said. "He plays physical and he goes all out. So [fans] can expect a little bit of a show from him this Sunday."

Jamie Han contributed reporting