INDIANAPOLIS — Peyton Manning knows all about falling apart in the playoffs. Though he struggled early yesterday, the Indianapolis Colts' stunningly stingy defense came to the rescue.

Manning and the Colts beat the inept Kansas City Chiefs, 23-8, yesterday, and while the star quarterback's numbers were good — 30 of 38 for 268 yards — his performance was mediocre. At least it was for the most prolific passer of his generation.

He threw three interceptions, didn't complete a deep pass and, ultimately, was bailed out by his defense.

"You have to keep playing," said Manning, who improved to 4-6 in the playoffs. "Every time you drop back to throw, your goal is to possess the ball on the next play. Three times, I was very poor on that. As soon as it gets you second-guessing, as soon as it gets you gun-shy, that's when you have problems."

The beleaguered Indianapolis defense was so good — or perhaps more accurately, Kansas City's offense was so bad — that Manning's miscues didn't stop the AFC South champions from advancing to the next round at Baltimore on Saturday.

"Our defense was awesome today," Manning said. "We made some mistakes and the defense made sure we didn't pay for it."

A defense that yielded 173 yards rushing per game this season allowed only 44 to Pro Bowl back Larry Johnson and the Chiefs.

Kansas City's initial first down came with 3:34 remaining in the third quarter. Indianapolis had four sacks, two by Dwight Freeney, and two interceptions. The Chiefs managed 126 total yards.

"We heard it all about having the worst defense," Freeney said. "Now we can hear this: We have the best run defense in the playoffs."

Meanwhile, Adam Vinatieri made three field goals and rookie Joseph Addai rushed for 122 yards and a TD for the Colts (13-4). Wisely, with Manning unable to throw deep, Indianapolis gave Kansas City (9-8) a steady dose of short passes that wore out the Chiefs.

That was most evident after Kansas City finally woke up and drove 60 yards to a 6-yard touchdown catch by Tony Gonzalez with 8 seconds remaining in the third period. Then the Colts went 71 yards on nine plays, mostly victimizing the Chiefs' linebackers underneath. Reggie Wayne caught a 5-yard TD pass to make it 23-8.

When Bob Sanders intercepted Green's desperate lob with just more than 6 minutes remaining, the Colts could start making travel plans for Baltimore — the city they left 23 years ago.

"It's a big challenge," Manning said. "Playing Baltimore is tough enough, but to go there — I think it's one of the tougher places to play. And they've been off a week and are fresh."

Until falling behind 16-0, the Chiefs looked like a team surprised to have made the playoffs, which they did last Sunday with a lot of help from other clubs. Johnson, who rushed for 1,789 yards and 17 TDs this season, was never a factor. He had only 32 yards on 13 carries.

"If we can't do what we do best, it amps them up," Johnson said. "And they certainly got amped up."

And while Manning's favorite receiver, Marvin Harrison, also had little impact, tight end Dallas Clark, in just his second game back from a knee injury, had nine catches for 103 yards.

"The way Kansas City's defense was, there were very few times we'd get a true single coverage outside on Marvin and Reggie," Manning said. "Play action to get the ball downfield was not there. But our running backs did such a great job of getting open and catching the ball and what we call 'going north.'

"Those checkdowns turned into 12-yard gains, and that's a real positive for the offense."