The Vikings are 2-2, well-rested from a bye week and back home, where they're 7-3 under coach Mike Zimmer. The Chiefs are 1-4, coming off a home loss to the Bears and will travel to Minnesota without their offensive identity now that running back Jamaal Charles is out for the season because of a torn ACL in his right knee.

With that in mind, Zimmer was tossed a question he probably hasn't heard in his 20 games and nine victories as an NFL head coach. Essentially, he was asked if he's worried his team will take the Chiefs too lightly this week.

"No, not really," he said. "We've only won two games, so no, not at all."

Questions about overconfidence don't typically make their way into NFL markets, particularly the ones sporting .500 teams. But that's how low the Chiefs are flying right now.

First, there's the sting of the last-minute, 18-17 loss as 9½-point favorites at home against a sub-.500 Bears team rocked by injuries. Worse yet is what the future holds because of just how hard this team leans on Charles to overcome the considerable deficiencies of quarterback Alex Smith.

Since Charles returned from a torn ACL in his left knee in 2012, he has accounted for 30.9 percent of the Chiefs' offense. According to ESPN, the only player to produce a larger percentage of his team's offense during that time is Bears running back Matt Forte (31.2).

"It changes things a little for them just because of how much he normally does for them," Vikings nose tackle Linval Joseph said. "But they're an NFL team. They have more than Jamaal."

But they don't have a quarterback who plays with consistent poise when he's under pressure. Yes, Smith can create headaches by running for first downs on third-and-long. But he's been sacked so many times (21) that he often hurries even when it's unnecessary. That creates mistakes and inaccuracy.

Charles was a great bailout option for a jittery quarterback and a weak offensive line. Dump the ball or hand it off to Jamaal and watch him explode.

The Chiefs aren't expected to change their offense. With Smith's limitations, there isn't much different they can do.

Usually, when teams take away Kansas City's screen game and dare Smith to push the ball down the field, the QB fails, as he did Sunday.

Charles' workload will fall on Charcandrick West and Knile Davis. West, undrafted a year ago, has 12 career carries, including seven for 31 yards on Sunday. Davis has two career 100-yard games.

"West is more similar to Jamaal," linebacker Chad Greenway said. "And every week, it's the same thing. Every NFL team has a great running back. Every NFL team has great receivers. And they all have good quarterbacks. Every one of those guys can beat you. I guess it gets redundant, but we just have to play our game and play well."

Zimmer also sounds more concerned about the Vikings than the Chiefs.

"Every day, I come in here and try to figure out how we can be better," Zimmer said. "Obviously, you game plan for people and things like that, but this league is so good. There are so many great players, there are so many teams that you don't expect to win that win each and every day. The teams that end up with good records usually find ways to win. And that's all we're trying to do."

The NFL has six undefeated teams. Each of them, except for New England, has had to scramble at some point to overcome flawed performances that easily could have gotten them beat.

The Falcons needed overtime to beat the Redskins and become the first 5-0 team in NFL history to trail in the fourth quarter in four games. Meanwhile, the Broncos (5-0) won for the second time when not scoring an offensive touchdown.

Even Aaron Rodgers looked human Sunday. He turned the ball over three times for the first time since 2009, but the Packers (5-0) found a way to beat St. Louis by 14 points to take a 2½-game lead over the Vikings in the NFC North.

"I think it's a great division," Zimmer said. "But I'm so focused on us, to be honest with you. I know what the records are. I know who is leading the division. But we've got 12 more games to go. … Let's add them up at the end of the year and see what happens."

Mark Craig mark.craig@startribune.com