The latest Chiefs defensive player to miss a practice was Jovan Belcher, a starting inside linebacker. The Chiefs said Belcher had a sore groin muscle on Thursday.

He was replaced by veteran backup Brandon Siler.

The Chiefs have six defensive starters who either will not be available or have a playing status in question for Sunday’s regular-season opener against Atlanta at Arrowhead Stadium.

“I’ve got what I’ve got and we’re going to go to battle with what we have,’’ coach Romeo Crennel said. “That’s what you have to do in this business.’’

Siler was a seventh-round pick by the Chargers in 2007. He started 12 games for San Diego over four seasons before joining the Chiefs last year.

But he missed all of the season because of a torn Achilles tendon.

“He’s a tough, physical player,’’ Crennel said. “He knows the game plan and understands the game plan, plus he’s had some experience. He was at (San Diego) for awhile and they were playing a similar defense to ours.’’

Other injuries

Belcher and two other defensive starters, free safety Kendrick Lewis (shoulder) and nose tackle Anthony Toribio (ankle), did not practice Thursday, along with reserve defensive lineman Allen Bailey,

Two defensive starters, linebacker Derrick Johnson (ankle) and cornerback Brandon Flowers (foot) were limited participants, along with reserve cornerback Jalil Brown.

Linebacker Tamba Hali has been suspended for the game by the NFL for a violation of the league’s substance-abuse policy.

Johnson sounded optimistic he would play against Atlanta.

“It’s still a little (sore), but it’s football,’’ Johnson said. “You’re never 100 percent out there. As long as I get enough confidence that I can run around and make plays and not hurt the team, I’ll be out there Sunday.

“I’m expecting to play. My mindset is not to sit out this game. I’ve got to play. It’s one of those things where you’ve got to step up as a leader knowing that you’ve got to play through some pain. As long as I don’t tweak it or hurt it before the game, I’ll be better than I was today.

“I’m looking forward to playing (against) the Falcons.’’

Waiting on Flowers

Crennel suggested a decision on Flowers would be made before the game Sunday when the Chiefs must declare seven inactive players.

“Maybe Sunday, about an hour and a half before the game,’’ Crennel said when asked when he would know about Flowers’ availability. “That’s the cutdown date, right there.

“You have to look at it objectively and you have to (weigh) the first game versus 15 others and having a guy available for 15. I think that plays a big part in it. You as a coach have to do what you think is best for your team for the season.’’

Falcons coordinators pose dilemma

Although Atlanta was a playoff team last season, the Falcons have new offensive and defensive coordinators, which puts the Chiefs in a little bit of a bind preparing for Sunday’s opener.

Do the Chiefs trust preseason Falcons tapes or go back and look at what new defensive coordinator Mike Nolan and offensive coordinator Dirk Koetter did at previous stops?

“When you have new coordinators, you just don’t know exactly what you might get,” Crennel said. “I know that coordinators have their things that they like and things that they feel like will work against a particular style of offense or particular style of defense.

“They’re going to tweak it the way they want to tweak it, and sometimes in the preseason you don’t see all of their tweaks because they’re still trying to evaluate young players as well.”

Nolan, a former head coach with San Francisco, and Chiefs offensive coordinator Brian Daboll were in the same positions last season with the Miami Dolphins.

“Brian is a very intelligent and great football coach,’’ Nolan told Atlanta reporters. “I was very impressed with him at Miami. Players like to play for him because he tries to utilize all of the players’ strengths. They have a lot of explosive players. I guess his biggest problem is who is he going to give the ball to next, because I’m sure he has a lot of guys who want the ball.’’