CHARLOTTE – So Jeremiah Sirles, the Panthers' right tackle with three starting offensive linemen currently out with knee injuries, how are the spirits in the position room?

"It's not like these guys have died," Sirles said. "Morale is good."

From that perspective, the news that left tackle Matt Kalil had surgery Monday, joining right tackle Daryl Williams and left guard Amini Silatolu as a sidelined starters, doesn't seem that tragic.

There also are other reasons that panic hasn't set in around Bank of America Stadium – and Sirles stands among them. Head coach Ron Rivera is encouraged by how the veteran with experience in a similar situation has stepped up and how a relative newcomer in Taylor Moton has done even more of the same. Rivera also likes what he's seen from Greg Van Roten, currently holding down the left guard job.

The other good news? None among the sidelined trio suffered a season-ending injury, and the season opener is still 19 days away.

"We have time," Rivera said. "We're still in the middle of training camp. We've got a number of guys that have opportunities, and we'll get those guys back because none of those were season ending, thank goodness.

"Now it's just a matter of time; we'll see how it all unfolds."

As the sun peaked through during an overcast practice Tuesday, a silver lining in the form of Williams worked on the side for the first time since injuring his right knee early in training camp. Rivera said he and Kalil – who is also recovering from a right knee injury, remain "week-by-week," but Rivera described Silatolu (left knee) as "day-by-day."

It's too early to forecast the likelihood that any of them will play Week 1 against the Cowboys, but the Panthers aren't sitting on their hands. Rivera described general manager Marty Hurney as "busy" when it comes to keeping an eye on possible additions not currently on the roster, but Rivera is excited about the ability and versatility of those already on the roster.