CHARLOTTE, N.C. -- Carolina Panthers coach Ron Rivera would not address an ESPN report Sunday that Pro Bowl middle linebacker Luke Kuechly did not receive a concussion during last Thursday night’s loss to Philadelphia.

“The biggest thing is he’s in the protocol, he’s advancing it and we’ll just see how he is tomorrow," Rivera said Tuesday as the Panthers (4-2) returned from a three-day break.

Kuechly did not practice Tuesday, but he did participate in stretching and light running. He also stayed involved with the defense as it planned for Sunday’s game at Chicago.

“He had a good day, and we’ll see how he is tomorrow," Rivera said.

Kuechly was placed in the concussion protocol for the third time in three years Thursday night after taking a hit to the shoulder and neck area late in the first half of a 28-23 loss to the Eagles.

ESPN’s Adam Schefter, citing sources, reported Sunday that team officials did not believe Kuechly had a concussion. The team quickly released a statement via Twitter saying Kuechly remained in the concussion protocol.

Regardless of whether Kuechly suffered a concussion or not, once a player is in the protocol, he has to pass all five steps to return.

Those steps are: 1. Rest and recovery; 2. Light aerobic exercise; 3. Continued aerobic exercise and introduction of strength training; 4. Football-specific activities; and 5. Full football activity and clearance from an independent neurological consultant assigned to the team.

It is not clear by what Kuechly did Tuesday whether he is in the second or third step, only that he is advancing.

Kuechly missed three games in 2015 with a concussion suffered in the opener. He was in the concussion protocol three games last season and held out the final three games with the Panthers out of playoff contention.

Rivera said the approach will be the same with Kuechly now as it was last year, so there are no guarantees the 2013 NFL Defensive Player of the Year will suit up against the Bears even if cleared from the protocol.

“The approach will never be different," Rivera said. “He’ll be in the protocol until the doctors tell me otherwise, and then we’ll make decisions based on that from there."

Third-year player David Mayo replaced Kuechly against Philadelphia and will start against Chicago if Kuechly does not play. While Rivera was pleased with Mayo’s play against Philadelphia, he admitted the defense isn’t the same without Kuechly.

“Luke is a special player," Rivera said. “It’s one of those things that Luke has built so much trust with his teammates that some guys feel that if they don’t make the play, Luke is going to make the play. They expect Luke to do so much for them."

Rivera compared what Kuechly does for the defense to what Pro Bowl center Ryan Kalil does for the offense in terms of communication on the line.

Kalil practiced Tuesday and is optimistic he can play for the first time since a neck injury sidelined him before the second game.

“I was fortunate enough that I played with one named Mike Singletary, He was a Hall of Famer," Rivera said of the former Bears middle linebacker, a player Kuechly often is compared to. “I was fortunate enough to have coached one in Brian Urlacher. Those guys literally could tell you prior to the snap what everybody does.

“Certain guys have that type of ability, have that knack."

Carolina end Julius Peppers, returning to face a Chicago team he played for from 2010 to 2013, said the absence of Kuechly “leaves a hole" in the defense.

“He leaves a void in the defense. The main communicator. Leadership. All those things we miss when he’s not out there," Peppers said. “Hopefully, he gets well soon. If not, we’ll do fine without him.

“But you can’t replace players like that. He’s a special guy. Hopefully, he’s fine in his personal life. That’s what we’re really concerned about."