KANSAS CITY, Mo. (AP) -- The Kansas City Chiefs and Denver Broncos appeared to be the class of the AFC West just a couple of weeks ago, and maybe the entire league, after going a combined 8-1 to start the season.
They're a combined 0-4 since then.
The Chiefs were humbled by Pittsburgh before dropping a heartbreaker in Oakland, which snapped their 12-game division winning streak.
And the Broncos were embarrassed by the Giants before getting shut out last week by the Chargers -- the first time they've been blanked in 25 years.
Now, what looked as if it would be a showdown for league supremacy on Monday night at Arrowhead Stadium has turned into a game matching two teams desperate to get back on track.
"Guys are frustrated. We know we can play better and we want to play better," Broncos quarterback Trevor Siemian said.
"Guys are a little frustrated. That's a good thing, I think. Me specifically, I have to play better. I know that. I think this week, more than ever, is a really big week for us."
That's because the division race is still wide open nearing the midway point. The Chiefs (5-2) are still on top, while the Broncos (3-3) are just a half-game ahead of the Chargers and Raiders.
"Every week the games just get bigger and bigger," Broncos cornerback Aqib Talib said. "Until you win the Super Bowl, games just get bigger and bigger. This is our next game and it's a huge game for us."
It's just as huge for the Chiefs, whose five straight wins sent them soaring to the top of just about every NFL power ranking.
But their high-powered offense was effectively shut down by Pittsburgh, and their suspect defense was exposed in their last-second loss to the Raiders.
Still, veteran quarterback Alex Smith is playing at a high level. Running back Kareem Hunt has gone over 100 yards from scrimmage in an NFL-record seven straight games to begin his career. Tyreek Hill has not lost an ounce of the speed that has made him one of the league's most dynamic players.
Defensively, there's still Justin Houston and Marcus Peters making life miserable for QBs.
"A lot of fingers can be pointed and all of that, but the reality is you're 5-2 and a pretty good football team," Chiefs coach Andy Reid said.
"There's always a little positive within the negative. It's hard right now, because you went 5-0 and then you have two losses and it seems like the whole world is falling apart. But in reality that's not the case."
It might be if the Chiefs lost to the Broncos at Arrowhead Stadium.
As the bitter rivals prepare for a primetime matchup, here are some things to know:
JAMAAL IS BACK:The Chiefs' career rushing leader, Jamaal Charles will return to Kansas City for the first time as a member of the Broncos. He was released last offseason when the Chiefs needed to save salary cap space and signed a one-year deal with Denver.
"It'll be great to be back where I started at," he said. "It'll be great to come back, but hearing the crowd will be different for me."
ERRORLESS ALEX: One reason Smith is having an MVP-caliber season has been his mistake-free play. He has thrown 15 touchdown passes without an interception, and needs five more TD tosses to match the league record for most without a pick to start a season set by Peyton Manning in 2013.
"To be honest, there's no time to reflect," he said. "You're just coming off a loss and you're in the middle of the season and all that stuff means nothing at this point. That stuff's for after the season. Two in a row, we've got a long time to think about this and hopefully get back healthy."
SPEAKING OF QBS:Broncos coach Vance Joseph insisted Siemian remains his starter, despite a series of poor performances.
But with Brock Osweiler up to speed and Paxton Lynch returning to practice for the first time since late-August, when he sprained his shoulder, the lease on Siemian could be short. "He's still working through the injury," Joseph said of Lynch. "Brock's looked fine. Brock's very engaged, very smart and a great leader. He looked fine in practice."
GETTING HEALTHY: The Chiefs could be buoyed by the return of three starters this week. Right guard Laurent Duvernay-Tardif (knee injury), center Mitch Morse (foot injury) and cornerback Steven Nelson (concussion) were all at practice this week and could be on the field Monday night.
STRENGTH VS STRENGTH: Might as well call it weakness vs weakness, too. The Chiefs have the NFL's top rushing offense while the Broncos have the league's second-best run defense, and Kansas City has the No. 3 overall offense while the Denver defense is ranked No. 1.
On the flip side, the Broncos have had trouble moving the ball and the Chiefs' defense is ranked 29th in the league. "We plan on taking care of the run game because that's what their team thrives off of," Broncos linebacker Shane Ray said. "It's a division rivalry, so it's going to come down to who wins the fourth quarter."