Kansas City, Mo. ? Even before he was hired in January, Chiefs coach Andy Reid watched tapes from every game that Kansas City played last season, including both matchups with the Broncos.

He undoubtedly noticed the 5-foot-9 cornerbacks that the Chiefs tried to match up with the bigger, stronger Denver wide receivers. And he certainly saw Demaryius Thomas and Eric Decker haul in 14 catches between them in what turned into a 38-3 rout last December.

So when Reid was hired, and John Dorsey brought in as general manager, they began reshaping the Kansas City roster.

They signed 6-foot-3 cornerback Sean Smith in free agency, along with hard-hitting veteran Dunta Robinson. They then plucked Marcus Cooper, a 6-2 rookie, off waivers from San Francisco, and added a couple other big defensive backs in Husain Abdullah and Ron Parker.

The result is a defense that’s suddenly built for the Broncos.

Even if Reid won’t quite admit it.

“You know, I think I’d tell you that you’re not sitting here building your team to beat the Denver Broncos,” he said. “That’s not what you’re doing. There’s a fine line there. You’re trying to accumulate all the best players you can at all the positions so you can compete not only with the Denver Broncos but with all the other teams in the NFL.

“That’s really what you’re doing,” Reid said. “To say that John sat there and brought in players that we could match up with Denver, I don’t think that’s the way it went.”

It’s the way it turned out, though.

Javier Arenas, one of those diminutive cornerbacks, was traded to the Cardinals. The Chiefs also jettisoned Jalil Brown, another of their backup cornerbacks.

The result of all those moves is one of the most bruising, physical defensive backfields in the NFL, and one that the Chiefs (9-0) believe can match up well Sunday with Thomas — at 6-3, 230 pounds, a matchup problem for anybody — and Decker, who’s a rangy 6-3.

“We always have confidence in our defensive backfield, no matter who we play,” said Brandon Flowers, the lone 5-9 holdover from last season. “We feel we match up pretty good with them.”

So good, in fact, that Flowers has slid inside the past couple of games and started to cover slot receivers. The idea was to prepare the Chiefs’ best cover cornerback to deal with the quicker but smaller Wes Welker, leaving the bigger Smith and Cooper to cover Thomas and Decker.

“They’ve got a lot more size than last year. Last year they had two smaller guys outside,” said Thomas, who’s coming off a three-touchdown performance against San Diego. “They’ve got 6-2, 6-3 and Sean, he’s about 220, so there’s some big guys there. If you let them get their hands on you, you’re going to have a long day.”

Thomas isn’t the only one in the Denver film room who’s noticed the Chiefs’ revamped look.

“Certainly when you’re playing the team, you approach the Chiefs this week, you study their personnel hard, you’re aware of which players they added,” Peyton Manning said. “They have some new players in the secondary from last year that are playing well for them.”