CHARLOTTE, N.C. -- A mixture of tears and sweat poured down the face of Carolina Panthers linebacker Luke Kuechly as he was carted off the field with a potential concussion late in the fourth quarter of Thursday night’s win against New Orleans.

He looked dazed.

Scared.

Teammates looked the same as they watched the 2013 NFL Defensive Player of the Year disappear into the tunnel at Bank of America Stadium, struggling to breathe as he fought back emotion.

"You could see it on his face that he was pretty visibly upset," tight end Greg Olsen said after Carolina’s 23-20 victory.

The season that began with the fear of being defined by the "Super Bowl hangover" all of a sudden is being defined by head injuries.

Kuechly, who is in the concussion protocol, could be the sixth Carolina player to suffer a concussion this season. Left tackle Michael Oher has missed seven games with one and there is no sign of when he will return.

Quarterback Cam Newton missed a Week 5 game against Tampa Bay. Backup safety and special teams ace Colin Jones has missed the past two games. Outside linebacker A.J. Klein missed Thursday’s game.

Cornerback Daryl Worley might have missed a game with one had Carolina not had a bye the week after he suffered his in Week 6 in New Orleans.

Concussions are scary because so much is unknown about them. The Saints put starting cornerback P.J. Williams on injured reserve in September three days after he was carted off with a concussion.

Former Carolina middle linebacker Dan Morgan missed the final 15 games of the 2006 season with what was believed to be at least his fifth concussion.

Once you’ve had one concussion, according to medical experts, there is a higher risk that you will have another.

This would be Kuechly’s second concussion in two years. He missed three games last season after suffering one late in the first quarter of the opener at Jacksonville.

Cornerback Kurt Coleman said the way Kuechly reacted when New Orleans running back Tim Hightower lowered his helmet into the middle linebacker’s facemask and chest was reminiscent of that hit.

Kuechly was hit so hard that he was pushed back into the path of outside linebacker Thomas Davis, whose helmet glanced off his teammate’s helmet.

It was such a somber sight as Kuechly laid motionless on the turf with team doctors evaluating him that Saints safety Roman Harper, who played for the Panthers in 2014 and '15, came to check on him.

Saints quarterback Drew Brees told Kuechly he was praying for him as the three-time Pro Bowl selection left the field.

"He is maybe, certainly one of the best football players I’ve ever seen -- ever played against," Brees said.

That the Panthers hung on to win 23-20 to keep their slim playoff hopes alive at 4-6 with six games remaining seemed less significant because of what happened not only to Kuechly, but center Ryan Kalil (shoulder) and defensive end Mario Addison (foot).

Kalil and Addison left the game earlier with injuries and did not return. Their status for Carolina's Nov. 27 game in Oakland remains uncertain.

But what is certain is it’s hard to imagine the Panthers making a playoff push without Kuechly. He’s had more tackles (693) than any NFL player since entering the league as a first-round pick out of Boston College in 2012.

He already had a season-high 14 tackles Thursday to give him a team-leading 102 this season before leaving the game.

If outside linebacker Davis is the heart of the defense, Kuechly is the soul.

His last words to teammates before leaving the field were to "keep fighting."

"Luke is a fighter," Coleman said. "That’s why we fight for each other."

Luke wanted me to let you guys know that he's doing fine and thanks for your prayers!! #KeepPounding A photo posted by td58 (@td58) on Nov 18, 2016 at 8:47am PST

This isn’t to suggest the Panthers can’t win without Kuechly. They beat Houston, New Orleans and Tampa Bay without him a year ago, with Klein taking over in the middle.

But with a young secondary, as much as it has improved during the past month, Carolina still needs Kuechly’s experience and ability to make plays that others simply can’t.

"That’s our leader, one of the key components of our team," fullback Mike Tolbert said.

The blank stare Kuechly had as he left the field wasn’t much different than the look on the faces of many of his teammates in the locker room afterward. The next-man-up mantra was repeated throughout, but there is no next man on the roster as good as Kuechly.

Not even close.

That’s why the winning locker room didn’t look much different than the losing locker room in terms of the mood.

"You just hope he’s OK more than anything," Olsen said. "When he comes back is out the window."