Mike Tomlin believes the Pittsburgh Steelers are "not a good football group right now" after a shock loss to the Cincinnati Bengals.
After starting the NFL season 11-0, the Steelers slumped to a third straight loss, beaten 27-17 by rivals the Bengals on Monday.
Pittsburgh were on an 11-match winning streak over Cincinnati, but fell to defeat to leave the AFC North up for grabs.
Steelers head coach Tomlin lamented his side's performance at Paul Brown Stadium as Pittsburgh became the first team in NFL history to lose multiple games in which they entered with 11-plus wins and their opponents had four or fewer.
"Just not good enough for us," he told a news conference.
"The performance speaks for itself. We turned the ball over at the early portions of the game, you can't do that, you can't do that versus anybody. We gave them the short field three times in the first half or so and so it was an uphill battle the rest of the way because of that.
"They were able to hide the ball a little bit because of those circumstances. I thought they had a good plan. You've got to tip your cap to them, particularly with some of the quarterback design runs, they were able to keep us off balance and minimise some of the things that we were able to do on possession downs so I want to give them credit, but largely we've got a lot of work to do.
"We're not a good football group right now and so we understand the consequences that come with that, we're working on a short week, we've got to be better than what we've been and that's just the reality of it."
Steelers quarterback Ben Roethlisberger struggled, completing 20 of 38 passes for 170 yards, a touchdown and an interception.
Roethlisberger became the seventh quarterback in NFL history to reach 60,000 passing yards, but he was well below his best.
"It's not injury related. It just wasn't good enough, like all of us, me included. We've got to be better," Tomlin said about his QB.
Roethlisberger also said he needed to improve, telling reporters: "Their whole defense kept us off balance. I wasn't good enough."