Arms folded, with lips poked out of frowned faces. Their body language pretty much summed up how most of Bronco Nation had been living of late. That would be disappointed, if not fed up, with little to cheer about during a three-game losing streak at Invesco Field at Mile High.

One short Jay Cutler touchdown toss to Brandon Marshall in the fourth quarter changed those frowns to smiles as the Broncos went ahead 24-17. Then it fell on the shoulders of the defense to protect that lead - Denver's first in 14 quarters at home dating to the second quarter against Jacksonville on Oct. 12.

The defense did its job, stopping a Chiefs drive 1 yard short of the Broncos goal line. Then Denver's offense ran out the clock to put the finishing touches on an AFC West title tie-clinching victory.

One more win - or San Diego Chargers loss - puts the Broncos in the playoffs for the first time since 2005. Against the Chiefs, the Broncos showed they are capable of overcoming early mistakes at home to win a game.

Defensive back Maurice Leggett returned an interception for a touchdown - Cutler's eighth interception at home and sixth in the past four home games - giving K.C. a 10-0 first-quarter lead.

Instead of poking out their lips, the Broncos offense responded with an 11-play, 80-yard drive capped by the team's longest scoring run of the season, an 18-yard dash by rookie Peyton Hillis.

Hillis would leave the game later with a hamstring injury that might sideline him for the rest of the regular season. Tatum Bell stepped in and gained 52 yards - including a toss sweep that produced 28 yards - Denver's second-longest run of the season.

This Broncos team that seems bonded together by glue, guts and a glut of rookies, is 8-5, having won four of its past five games. They held an opponent under 20 points in consecutive weeks for the first time since 2006. And Cutler was not sacked in 40 pass attempts. He's been sacked just twice in 278 attempts at home this season.

"It's not like some other teams with top-five draft picks," cornerback Dre Bly said. "We've got undrafted guys, guys getting opportunities to play in this league and they're playing well. And I'm happy for those guys because this is what it's all about, making the most of every opportunity."

They're young. They're sturdy. They make mistakes. They are the Broncos, the team CBS analyst Bill Cowher declared on Sunday to be "the most dangerous" in the AFC.

Up three games in the division with three games left to play. The Broncos don't need binoculars to find the playoffs. The postseason is staring them in the face.