CINCINNATI -- The Cincinnati Bengals’ locker room had none of the joy on Sunday night it had shown en route to a 4-1 record.

Dre Kirkpatrick looked emotional as he described how it felt to lose to the Pittsburgh Steelers for the sixth straight time. Nick Vigil walked out on crutches. Darqueze Dennard had his arm in a sling. And defensive end Carlos Dunlap, who has been through this time and time again, was the last to talk, holding court in an empty locker room.

Dunlap told reporters they picked a good day to talk to him. It was as if he had something he wanted to get off his chest.

"Insanity is when you keep doing the same thing over and over and expect different results," he said. "We made some mistakes that we made before. We've got to learn from them. Once again."

There was a resounding feeling around the locker room that the better team had come out with the L after the Steelers scored a touchdown within the last minute. They all said they didn’t finish, which has been a theme in the past but not this year.

Players have said in the past that they felt they were the better team, even after losses to the Steelers. The comments from Sunday could’ve come from years past. The mantra has remained the same.

The question now is: What do they do about it?

The Bengals have a tough task ahead with the Kansas City Chiefs up next. The 5-1 Chiefs look like one of the best teams in the league, and they certainly have the best offense, averaging 35.8 points-per-game. They lost for the first time this season on Sunday, and yet still put up 40 points on the Patriots.

The Bengals, meanwhile, are struggling on defense. They managed to keep the Steelers in check for most of the game and even tightened up in the red zone several times to force field goals. But when it came down to it, given one minute and the crucial need to keep the Steelers on their side of the field, they couldn’t do it.

It didn’t help that their defense was down to its bare bones after losing three starters during the game, but every player would say the league is all about next man up.

"Football has a 99 percent injury rate. People are going to get hit, people are going to get dinged up. You do what you do to take care of your body and get ready to play next week if you can,” Dunlap said.

It’s easy to say the Bengals face one of their biggest tests every week. The Steelers game was certainly one, but this week is just as important. The Bengals have one of the youngest rosters in the league, and none of the players has gone through any real adversity this season. Now is the point where they show if they’re truly tough.

Bengals wide receiver John Ross was asked last week what’s different about the team, and he pointed out how easy everything is when the wins are piling up.

Now their true character test comes after a tough loss.

The Bengals are going to have to figure out why their defense failed at the worst moment, whether it’s a problem on the players' side (Kirkpatrick’s late holding penalty, for example), or the scheme.

A few players pointed out that Ben Roethlisberger seemed to know what they were doing on defense late, perhaps a byproduct of being so familiar with the Bengals. The Bengals were in cover zero on the touchdown play, meaning they called an all-out blitz, anticipating it would be a run play to set up a field goal.

“I think he just knew how we were lined up,” safety Clayton Fejedelem said. “I mean, everyone was right there in front of him and that’s how we were lined up on a few of our goal-line plays. He’d seen it a couple times [today] already.”

The Bengals also essentially got no pressure on Roethlisberger, save for one play in which nose tackle Andrew Billings pushed the pocket enough to get Roethlisberger to roll out and throw an incomplete pass. Considering the talent on the defensive line, it was certainly head scratching.

If there’s a tape of mistakes to learn from, it will certainly be this one. And with the possibility of being shorthanded this week on defense, there won’t be much time to look back. The Bengals are going to have to look forward, and quickly, or they could be facing their first losing streak of 2018.

“We’ll be back next weekend,” wide receiver Tyler Boyd said. “We’re going to get the win.”