Linebacker Rey Maualuga knew the Bengals' defense had slipped against the run this season. He didn't realize it was in such a free-fall.

"I don't even know where we're at," he said, guessing at their league ranking. "Twenty-something?"

Nope. Try 31st. Yes, second to last.

"Ooh, wee!" he said with a grimace.

A defense that was one of the NFL's best last season can't even stop the run nowadays, and it's pulling down a three-time playoff team that's in danger of not making it for a fourth year in a row.

The Bengals (5-3-1) are still in the AFC North race — everybody is — and in line to get a wild-card berth if that doesn't pan out. But after starting the season with three straight wins, they've gone into a 2-3-1 slump that starts with the defense.

Until that part gets better, the Bengals are going to struggle.

"It's Football 101," linebacker Emmanuel Lamur said. "It's all about responding back. We can't have our heads down because of a few games. We know we've got to go out there and fix what we've got to do and get better."

They're starting the toughest part of their schedule. Five of the last seven games are on the road, with one of the home games on a Monday night against Denver. Their game on Sunday at New Orleans (4-5) is the first of three in a row on the road.

It's a stunning about-face on defense. The Bengals returned the unit virtually intact after finishing third overall last season. The biggest change was with coordinator Mike Zimmer leaving to become the head coach in Minnesota.

The defense played well during that 3-0 start. Things have fallen apart in the last six games, with opponents rushing for at least 170 yards three times. Cleveland had 170 during a 24-3 victory at Paul Brown Stadium last Thursday night.

Cincinnati's defense ranks 30th overall. The Bengals have finished in the top seven in defense four of the last five years.

Injuries have been a significant factor, especially at linebacker.

Vontaze Burfict made his first Pro Bowl last season, but hasn't been able to stay healthy. He missed two full games and parts of others with concussions. He also had surgery to clean out his left knee on Oct. 29 and will miss his third consecutive game on Sunday.

Maualuga has missed the last four games with a strained left hamstring. He returned to practice this week on a limited basis and was listed Friday as questionable to play in New Orleans. Maualuga is known for his ability to stop the run.

"We've had a number of different guys in there, that's part of the issue," coordinator Paul Guenther said. "I can't tell you how many different sets of linebackers and combinations we have had in there, so it's something we have to work through.

"I know what it's supposed to look like. Obviously, if Rey comes back it will be a big help. That will clean some stuff up for us."

Missing Burfict has been a significant setback. He's the leader of the defense and makes sure everyone knows what's going on with every play. It's unclear how long Burfict will be out. He didn't practice this week and was still walking with a slight limp in the locker room.

"Obviously it hurts with Vontaze not being here," Maualuga said. "He's like the Tasmanian Devil out there in the group. He's the type of guy that you would want out there on your team."

NOTES: Burfict and running back Giovani Bernard were ruled out Friday. Bernard will miss his third straight game with shoulder and hip injuries. Bernard didn't practice during the week. ... Right tackle Andre Smith is doubtful because of a sprained left ankle. He also missed the game against Cleveland. ... Cornerbacks Terence Newman (knee) and Leon Hall (concussion) were considered questionable.



AP NFL website: www.pro32.ap.org and www.twitter.com/AP_NFL