In fact, it seemed as if their confidence soared.
Andrew Luck answered by calmly picking apart the Chiefs defense, Donald Brown had touchdowns running and receiving, and the Colts didn't allow another point the rest of the way in a 23-7 victory Sunday that could turn into a preview of an AFC wild-card game.
If Indianapolis ends up as the No. 4 seed in the playoffs and with the Chiefs assured of the fifth seed, the two teams would meet again in two weeks at Lucas Oil Stadium. Kansas City's chances of winning the AFC West were dashed earlier Sunday when Denver beat Houston.
"There was no panic," said the Colts' Jerrell Freeman, who had two interceptions. "When they got that touchdown we were like, `Aww, it's OK.' It's just execution, and us not trying to panic."
Instead, it was the Chiefs (11-4) who looked as if they panicked.
Alex Smith threw for 153 yards, but he fumbled once and was picked off twice. Knile Davis also fumbled the ball away, and the Chiefs were hit with several key penalties that scuttled any chance of mounting a second-half comeback in the frigid weather at Arrowhead Stadium.
"We'll see them again," Chiefs linebacker Derrick Johnson said. "They've got the upper hand on us right now because in their minds they think they can beat us. If we go down there, it will be a different story. But we've got to fight our way back."
The AFC South-champion Colts (10-5) have beaten the Chiefs in five of their last six games.
Jamaal Charles ran for 106 yards and the game's opening score, but Kansas City failed to keep him involved as the Colts scored the final 23 points. Luck finished with 241 yards passing, while Brown gashed a decent run defense despite working behind a patchwork offensive line.
Adam Vinatieri also had three field goals for the Colts, who didn't commit a turnover.
"That's what coach (Chuck) Pagano has preached since I've been with the club," Luck said. "Limit turnovers on offense and create turnovers on defense."
Early on, the Chiefs appeared as if they were going to pick up right where they left off last week, when they hung 56 points on the Raiders. They marched downfield on the opening drive, and Charles took a carry around the right side 31 yards for a touchdown.
The Colts defense stiffened after that, though, and the closest Kansas City came to scoring again in the first half came when Ryan Succop yanked a 47-yard field goal wide left.
"It was a team effort in not a very good way," Chiefs coach Andy Reid said. "You can't pull your foot off the accelerator when you get out that quick."
Meanwhile, Indianapolis kept taking advantage of breakdowns in the Kansas City pass defense, the most glaring one coming after running back Knile Davis fumbled in the second quarter.
Brown leaked out of the backfield unnoticed by the Kansas City defense, Luck hit him with a dump-off pass that he took virtually untouched 33 yards for a score.
"I think they busted the coverage," Brown said, "so that made my job a lot easier."
Brown's job wasn't a whole lot tougher when the Colts got the ball back in the third quarter off Smith's interception. He raced through a gaping hole, then tight-rope walked down the sideline 51 yards for a score -- a video review showed that he somehow stayed inbounds.
Vinatieri added to the Colts' cushion with his third field goal, capping a drive kept alive by a defensive hold and a taunting penalty after the Chiefs had already held on third down.
Smith was picked off again by Freeman in the end zone midway through the fourth quarter, and then the quarterback fumbled the ball away with 3:24 left to seal the game.
"The way we opened up, marching down the way we did, it felt like things were going to be the way they've been," Smith said. "We really didn't get into a rhythm after that, didn't execute in any area, and then the turnovers. The turnovers hurt you."
Vinatieri has now scored 1,993 points, passing fellow kicker Jason Elam for seventh on the NFL's career list. ... Three of the Chiefs' four losses have come at Arrowhead Stadium. ... Kansas City had scored 101 points the last two weeks. ... The Colts started their seventh offensive line combination and fifth in five games.
The Atlanta Falcons have agreed to a five-year contract extension with wide receiver Julio Jones. Sources say he will receive $71.25 million total, with $47.5 million guaranteed.
Randall Cobb, who fell hard on his right shoulder on the third play in Saturday's 39-26 preseason loss to the Eagles, avoided major injury but will have additional tests done Sunday.
Redskins coach Jay Gruden said he was left like everyone else -- scratching his head over how Robert Griffin III went from being cleared one day to out the next with concussion symptoms.
Dallas Cowboys wide receiver Dez Bryant will go into the regular season without having taken a snap in the preseason.
Bengals QB Andy Dalton left Saturday's 21-10 preseason win over the Bears as a precaution with a neck injury that appeared to happen on his first and only series of the night.
Baltimore Ravens wide receiver Steve Smith and Washington Redskins cornerback Chris Culliver were ejected with less than a minute left in the first quarter of Saturday night's preseason game.