The chess metaphor has become a cliche in sports, but football, at its highest level, requires a similar skill: Your chances of success derive largely from your quarterback’s ability to read the board. When the Broncos play the Chiefs, it’s a pretty crowded board.

For the second time in three weeks, the Chiefs’ starting lineup Sunday against the Broncos was what is known as a dime defense, in which six of the 11 defensive players are cornerbacks and safeties.

Traditionally, a “base” defense consists of four defensive linemen, three linebackers, two cornerbacks and two safeties. Over the years, as rules changes have encouraged the crowd-pleasing passing game, offenses have deployed more receivers and defenses have responded with more defensive backs. The fifth defensive back was called the nickel back. The sixth made it a dime in something of a linguistic non sequitur.

These used to be situational packages. Against Peyton Manning, they are what you start with. At least, if you’re Chiefs defensive coordinator Bob Sutton, they are. In both matchups, the Chiefs started three cornerbacks (Sean Smith, Brandon Flowers and Marcus Cooper) and three safeties (Eric Berry, Quintin Demps and Kendrick Lewis).

Facing this maze of defensive backs two weeks ago, Manning chose the Cooper Gambit, for reasons not that difficult to divine. On one side of the formation, the defensive right side, the Chiefs deployed Smith, one of the bigger, better defensive backs in the game. In the middle, against Broncos slot receiver Wes Welker, they positioned Flowers, a somewhat overrated but also well-known cover corner. On the other side, the defensive left, they deployed Cooper, a rookie drafted by the San Francisco 49ers three picks before the draft ended, then cut at the end of training camp.

So Manning connected with Demaryius Thomas five times for 121 yards at Mile High in that first matchup, including a 70-yard bomb, on the way to a 27-17 Broncos victory. Thomas started the game split wide left, opposite Smith. When Manning flipped the formation, sending Eric Decker left and Thomas right, Smith stayed where he was and picked up Decker. So Manning feasted on the DT-Cooper matchup.

Afterward, I wondered why the Chiefs wouldn’t tell their best cover corner — Smith — to stick with the Broncos’ best wide receiver no matter where he lined up. Sunday, I learned the answer:

It doesn’t matter.

Decker is equally capable of exploiting a rookie defensive back. When Thomas hurt his shoulder on the Broncos’ first play from scrimmage Sunday, Manning turned to Decker. By the time he was finished, the Broncos had a 35-28 victory, a season sweep of the Chiefs and a clear path to the AFC West title.

On the way, Decker did something no Broncos receiver had ever done before, catching four touchdown passes in a game. He finished with eight catches for 174 yards and became just the 12th player in NFL history to post four receiving touchdowns and at least 170 receiving yards in the same game. Jerry Rice is the only one to do it twice. Other names on the list include Lance Alworth, Bob Hayes and Terrell Owens.

Cooper was covering Decker on two of the touchdowns, Flowers on the other two. Decker routinely fought Cooper off at the line of scrimmage and roamed free. The preview of coming attractions came midway through the second quarter, when he shook off Cooper at the line and beat him on an out-and-up that went for 42 yards to the Chiefs’ 3-yard line as the Broncos fought back from a 21-7 deficit.

“DT got hurt on the first play of the game,” Manning explained afterward.

Actually, he didn’t learn this until the end of the Broncos’ first offensive series, when he tried to pick up where he’d left off two weeks before, exploiting the Thomas-Cooper matchup with one of those jump balls that Thomas routinely snatches out of the air. This time, Thomas reached for it with only hand. The ball rolled down his arm and into the hands of Demps for an interception. Turned out that safety Lewis had slammed Thomas’s left shoulder on his first catch, after he’d beaten Cooper on a short slant.

“That third down to him, in that type of play, usually he can go up and make it,” Manning said. “He couldn’t even reach with his other hand. He goes up with one hand and obviously tips it, and it ends up getting intercepted. I probably told him he could have told me that earlier, that he only has one hand, and I might not have thrown to him.”

After that, it was pretty much Decker on the right side the rest of the way. Occasionally, Welker would come out of the game and Flowers would slide over, but mostly, it was the Cooper Gambit all over again. Even the one-armed Thomas eventually took advantage, catching a 77-yard fly route off him.

The rookie from Rutgers had his moments, including an interception of a Manning floater early in the second quarter, but by the time Decker’s record-setting day was over, it was obvious the master had read the board, found the weakness and battered it once more.

“I’m a corner,” Cooper explained. “That’s just the life I live. Sometimes things are going to work for me, sometimes things aren’t. I just have to keep going at it at practice and continue to learn.”

Asked about getting over such a tough day, Cooper said: “Peyton is a great quarterback. He’s going to make those plays. We just have to limit those. This is a learning experience.”

It was reminiscent of Darrent Williams, the late Broncos cornerback, after Manning, then with the Colts, took him to school back in 2006.

“It’s the great Peyton Manning,” Williams said then, with a smile. “That’s what I call him now.”

Sunday at Arrowhead, Manning completed 22 of 35 passes for 403 yards and five touchdowns. That gives him 41 touchdown passes for the season, breaking the Broncos’ franchise record with four games to play. The record — 37 — was set by Manning last year, his first with the Broncos. He is now nine shy of the NFL record, which is 50, set by Tom Brady in 2007.

Manning declined to acknowledge he targeted the Chiefs’ rookie cornerback for the second time in three weeks. Asked about the matchups, this is as much as he would say:

“They double (Wes) Welker often. In the two games we’ve played, we knew the double Wes was a scenario, so sometimes Eric is going to draw single coverage, and he played well. He ran good routes. I thought Adam (Gase) called some good plays. We were able to get down the field. Protection held up and allowed us to get down the field. Eric was awesome. Hats off to him and the way he played today.”

Decker’s wife and reality television co-star, Jessie James Decker, was somewhat more effusive on Twitter.

“Omg, omg, omg, I am crying,” she tweeted.

Manning was asked a second time about the Cooper Gambit.

“(Decker’s) touchdowns were on two different guys — Flowers, who is a top cover corner, and 31 (Cooper),” he said. “Those guys are good players. Hey, you’re not in the NFL unless you’re a good player. If you run good routes and you have time to make an accurate pass, sometimes it’s tough to defend. I really just give Decker more of the credit as opposed to saying we were going after one particular guy.”

Even with tight end Julius Thomas out with a knee injury and Demaryius Thomas hampered by the shoulder, the Broncos had more than enough offensive weapons. And even with all those defensive backs in the game, the Chiefs had not enough answers.

Once 9-0 and considered the best defense in football, the Chiefs are now 9-3 after being slapped around in consecutive weeks by the Broncos, Chargers and Broncos again. At 10-2, with the tie-breaker by virtue of beating the Chiefs twice, the Broncos have a clear path to the AFC West title and a first-round playoff bye.

As they learned last year, this guarantees them nothing, but it’s better than the alternatives.

“We came into a tough environment and got it done,” Jack Del Rio said after his fourth and final game as interim head coach. John Fox, who underwent open heart surgery four weeks ago to replace a valve, resumes his duties Monday. “I’m really proud of every man in the room and every guy that traveled, in terms of helping us get this win.”

The Broncos still have issues, of course. They surrendered 452 yards of offense to the Chiefs, not to mention a 108-yard kickoff return. They have the usual bumps and bruises of a team three-quarters of the way through a 16-game season.

But they’re back to their old ways, setting records on offense and playing just enough defense to win. When the elements cooperate — it was clear and mild in Kansas City — it’s going to take a pretty good chess player to beat them.