(AP) -- The Denver Broncos are comfortably atop the AFC West, but now they'll have to replace a key offensive contributor.
A dominant defense led by Von Miller should help soothe any concerns.
With Willis McGahee out, Miller and the defense could be poised for yet another dominant performance Sunday against the lowly Kansas City Chiefs.
Denver (7-3) opened a three-game lead in the West with a 30-23 victory over San Diego last Sunday, sweeping the season series.
The Broncos are on the cusp of matching their win total from last season thanks to a five-game winning streak, but they'll have to go forward without McGahee. The team leader with 731 rushing yards, McGahee was placed on injured reserve after tearing the medial collateral ligament in his right knee when he was tackled low against the Chargers.
McGahee will be replaced by rookie Ronnie Hillman, Lance Ball and former first-round pick Knowshon Moreno, who have combined for 297 yards and two TDs on 82 carries this season.
'"We're certainly going to miss Willis," quarterback Peyton Manning said. "To say we're not going to miss Willis would be not telling the truth because he's that good of a player. ... So, Knowshon and Ronnie and Lance have to step up. Everybody else has to step their game up, too, when you're missing one of your top players."
Manning doesn't have to worry about his defense, which ranks among the NFL's best allowing 312.8 yards per game, including 93.8 on the ground.
Denver's defense also leads the league with 35 sacks, with Miller recording seven of his 13 in the last three games. He had three against San Diego and is second in the league in that category.
"That boy works his butt off and plays with a lot of confidence, and I see him doing it for a long time," cornerback Champ Bailey said.
Miller's 24 1/2 sacks are the most by a Bronco in his first two seasons since the stat became official in 1982.
He figures to be in the Chiefs' backfield fairly often since they've allowed 10 sacks in four games after Brady Quinn was taken down three times and Matt Cassel once in last weekend's 28-6 home loss to Cincinnati.
Kansas City (1-9) is averaging 12.0 points during a seven-game losing streak, mustering just 166.0 passing yards over the last five contests.
"We know we have to fight. We have to do everything in our power to be the best we can be, to be perfect," coach Romeo Crennel said. "That's what I told them, we have to be perfect because that's the only way we have a chance."
The Chiefs, losers of all five home games, were far from perfect last weekend, converting only one third down and totaling just 284 yards of offense. That's partly why Crennel is going back to Quinn.
"I like his leadership qualities and he's had experience with a couple of different teams and he's seen a couple of different things," Crennel said of his former first-round pick, who has yet to break through as an NFL starter. "I think that will bode well for him."
Crennel may feel more comfortable with Quinn over Cassel since he spent the past two seasons as a backup with Denver, never appearing in an official game.
"I know I really enjoyed the teammates I had there. I tried to get better every day, and I think I got better," Quinn said. "I can't really speak about what did or didn't happen."
He's completed 24 of 42 passes for 181 yards with three interceptions in two starts this year.
Unlike the Chiefs, there's no doubt who will be under center for Denver.
Manning is looking for an improved effort after struggling by his standards last week. He completed 25 of 42 for 270 yards with three touchdowns and one interception, while getting sacked three times.
Protecting Manning will be even more important with McGahee out, and it's unclear if Hillman can contribute due to his size.
The rookie, noted for his speed, has 188 yards and a touchdown on 49 carries.
"You've got to protect Peyton a lot longer. I've been in there a lot, but if I do get an extended role, then it's a little more pressure, being able to do everything right every play that I'm there."
Manning threw five TDs in his last visit to Kansas City, leading Indianapolis to a 45-35 win on Oct. 31, 2004.
