Andrew Luck is busy breaking down film of his daily practice sessions, so the Colts' rookie quarterback hasn't had time to build up nerves for Sunday's preseason opener.

In fact, he doesn't even know how much action he'll see against St. Louis. No worrying and no lobbying. He'll start the game and play until he's told to take off his helmet.

"Whatever (the coaches) decide I'll just go with the flow," Luck said. "They know a lot more about football than I do."

Luck has been getting used to various environments, including Tuesday night's practice under the lights and practicing in front of throngs of fans. But no matter how focused he is on the day to day, Luck acknowledges Sunday will bring some added importance as his first NFL game action.

"I'll be nervous. I think I'll have some butterflies," he said. "That's happened throughout high school and college, so I assume it'll be the same at this stage."

Luck came to the Colts with a reputation as a student of the game, while also showing impressive athleticism at the scouting combine. But his arm strength has been noted by teammates.

"Until you catch it or try to bat it down, you don't see how much velocity it really has," outside linebacker Robert Mathis said. "He has a real strong arm. He's ahead of the curve. So that's a big plus for us."

That arm was on display with a few deep completions in practice, which led to the defense ramping up its intensity.

"Oh, yeah, he got us with a couple deep balls the other day," linebacker Pat Angerer said. "That kid can throw pretty good."

Luck quickly took ownership of the huddle, and has impressed his offensive linemen with his quick grasp of the offense.

"He's got great command of the huddle. That's his huddle," said guard Joe Reitz. "He's the commander and we are the troops."

Among the specific areas Luck continues to focus on include ball control, converting third downs and building chemistry with a new receiving corps.

"It's just not taking a dip or a lull practice-wise," Luck said of gauging his progress. "If you can put the film on and say, 'Okay, I made mistakes, but I didn't make the same mistakes I did the day before'. Not repeating mistakes really is what I'm trying to say."

Mathis, who is making the conversion from defensive end in the new 3-4 scheme, deemed Sunday's game a "stepping stone" for the retooled Colts.

It also means live game action at his new position, and a chance to hit opponents.

"To actually hit somebody else besides your own teammates, and to just get the frustrations out and to be able to take somebody to the ground a little bit, it's just a welcome change," Mathis said.

It's a new era for the Colts, which appears to have rejuvenated veterans like Mathis.

"Build a monster, that's what we're doing," he said. "So let's go."