"The game within the game was a point of emphasis for the Indianapolis Colts heading into Sunday's game against Denver at Lucas Oil Stadium, and the main reason they remained unbeaten.

When in the red zone, capitalize.

"We really wanted to get touchdowns in the red zone," quarterback Peyton Manning said. "That's where Denver can really tighten you up."

Not Sunday. The Colts' 28-16 win was a direct byproduct of the Manning-led offense finishing what it started. Four of the 13 drives penetrated the Broncos' 20-yard line. Three ended with touchdown passes to tight end Dallas Clark, the other with a TD to rookie receiver Austin Collie.

Clark's three TDs were a career high and pushed his career total to 39. He moved past Hall of Famer John Mackey (38) into second place in club history for tight ends, trailing only Jim Mutscheller (40).

Much of the afternoon, the Broncos tried to limit Clark's productivity by using cornerback Ty Law on him. In the red zone, the chore primarily went to linebacker Wesley Woodyard.

"We look for those kind of matchups," Manning said.

Clark won all three for 10-, 1- and 1-yard TDs.

It was the latest bit of success for the Colts' red-zone offense. In an 18-14 win over San Francisco on Nov. 1, it went 0-for-4 inside the 20. In the past six games, it's 17-for-23.

"We always stress that," Clark said of red-zone efficiency. "When we get in the red zone, we have to score touchdowns. It is so hard to get in the red zone, and it's so hard to move the ball. When you get that close, you have to capitalize.""