KANSAS CITY, Mo. -- One month ago, the Kansas City Chiefs had no reason to expect they could compete defensively against quarterback Dak Prescott and the high-scoring Dallas Cowboys.

The Chiefs had no productive pass rush to speak of. They regularly had key defensive starters missing from the lineup. Their young players weren't helping much. The Chiefs were allowing points and yards at a more than generous rate.

Fortunately for the Chiefs, their game against the Cowboys is Sunday at Arrowhead Stadium (4:25 p.m. ET, Fox), and things have changed dramatically in a month. The Cowboys lead the league in scoring and Prescott is the NFL's top-rated passer, but defense is no longer dragging the Chiefs down. They've allowed fewer than 16 points per game over their past five, which is third best in the league during that span.

This defensive transformation has largely escaped notice, overshadowed by improved play from quarterback Patrick Mahomes and the offense. But Mahomes has noticed.

"Don't let that get overlooked, how the defense is playing," Mahomes said. "That's going to make us a great football team."

There's no single factor for the defensive turnaround but a combination. The Chiefs had at least one key defensive player and sometimes more out of their lineup in each of the season's first eight games. They've been whole the past two games.

"Confidence is huge and [also] guys playing together snap after snap," defensive coordinator Steve Spagnuolo said. "When you go through an injured guy being out so you've got to plug another one in, it's tough. It's hard to get that continuity."

The Chiefs are still next to last in the league in sacks with 14, but their pass rush has perked up. They recently acquired veteran defensive end Melvin Ingram, giving them a fourth pass-rusher with at least 10 sacks in a season at some point during his career. Three of the Chiefs' top four games in terms of pass rush win rate have come in the past four weeks.

The Chiefs are getting better play from some of their young defensive players. Linebacker Willie Gay missed the first four games of the season with an injury but is tied for the team lead in interceptions with two. Linebacker Nick Bolton was the NFL's rookie of the month in October. The second-round pick out of Missouri has 47 tackles this season.

"The young guys are maturing quicker than you can predict," coach Andy Reid said. "You don't know exactly how that's going to go but they've picked up the pace and the scheme. And then Spags is relentless with them. He's going to make you do it until you get it right."

Cornerback L'Jarius Sneed played a lot as a rookie last year and after a slow start this season has begun to turn things around. Sneed had an interception in the win over the Green Bay Packers and made some key open field tackles in last week's victory against the Las Vegas Raiders.

"He's coming into his own," safety Tyrann Mathieu said. "I know he probably wasn't making the plays early in the season that I thought he would make, or that he thought. But he's coming along. I think the whole world will know his name by the end of the season."

The revitalized Chiefs defense will get it's biggest challenge of the season from the Cowboys, who are the NFL's only team among the top 5 in passing and rushing. But the Chiefs have come a long way on defense and don't intend to give back any ground now.

"We knew it was going to take some time," Mathieu said. "The last couple of years it took some time to start clicking. We believe in it. That's all that really matters. Our coaches are well-seasoned and experienced and we feel like we have a chance, we have a shot.

"We're going to continue to get better, just like the last couple of seasons. I see us being one of the better defenses when it matters the most."