As a sea of blue enveloped a sobbing Luke Kuechly before he was carted away, a lone white jersey stood nearby.

Roman Harper may have been on the opposite sideline Thursday night, but the Saints safety left it to be by his buddy’s side.

“Luke is a great friend of mine, and anytime you see one of your friends down it’s never a good thing,” said Harper, who signed with the Saints this offseason after spending the past two seasons in Carolina. “He’s not just an average guy to me. Seeing the way that he was, I was trying to get him to calm down and control himself.

“I know Luke. He’s trying to get back. He’s trying to battle it and not be hurt.”

But Kuechly was, no matter how much he or the suddenly silent Bank of America Stadium crowd wanted him to stand up and run off like everything was OK.

Shortly after the national TV broadcast speculated Kuechly injured his left leg, the Panthers announced he was being evaluated for a concussion, an injury that cost him three and a half games early in 2015. That occurred when Kuechly stuck his helmet into the chest of Jaguars running back T.J. Yeldon. Thursday night’s tackle was somewhat similar.

This time, the helmet of Saints running back Tim Hightower collided with Kuechly’s face mask. Then, as he was falling backward, the back of Kuechly’s helmet smacked the front of Thomas Davis’s.

Like in Jacksonville, Kuechly tried to get up before falling back to the turf. With tears in his eyes, he was loaded onto the cart, while his teammates — and Harper — wished him well.

“I just said, ‘You’re all right, big dog,’ as he was getting carted off and just let it go from there,” Harper said. “I think he’ll be OK. Once he gets out of the emotions and slows down, he’ll be all right.

“We just got to get him to calm down, and that’s why we asked (Davis) to go talk to him because TD is his brother.”

But not the only one.

“It’s a brotherhood,” Panthers safety Kurt Coleman said. “That’s the one thing that people don’t understand. Yeah, in between the lines we’re trying to battle, but it doesn’t matter what team you are.

“We all look out for each other because you never want to see a player go down like that. Even when (Saints running back) Mark (Ingram) went down (with a concussion), I was saying some prayers because this game is too tough and it’s too rough as it is.

“We sign up for it, but like I said, this is a brotherhood and we look out for each other.”