Indianapolis Colts quarterback Jacoby Brissett (7) runs away from pressure by Kansas City Chiefs defensive tackle Chris Jones, right, during the first half of an NFL football game in Kansas City, Mo., Sunday, Oct. 6, 2019. (AP Photo/Reed Hoffmann)

KANSAS CITY, Mo. (AP) — The way Indianapolis handled the Kansas City Chiefs on Sunday night sent a jolt through the NFL, whether it was dominating the line of scrimmage or shutting down Patrick Mahomes and Co. on defense.

The one place the shock didn’t reverberate? The visiting locker room in Arrowhead Stadium.

“The one emotion we were not feeling is shock. I can’t even explain it,” Colts coach Frank Reich said after the 19-13 victory. “The way guys were walking down the hallway, it was ‘We’re not going to be denied. We have to get on track. We’ve got to do it.’ I just knew it was real. I felt it all week.

“There was just an air of confidence and belief that we would do what we did today.”

Marlon Mack ran for 132 yards , and ageless kicker Adam Vinatieri knocked through four field goals, as the Colts atoned ever-so-slightly for a January playoff defeat inside the same stadium.

Asked what the message was pregame, longtime Chiefs linebacker-turned-Colts defensive end Justin Houston replied: “To come out here and play our game. To leave it out there every snap, to play with your heart, play with your soul. And I think we did that tonight.”

The Colts (3-2) allowed points on the Chiefs’ first two possessions before shutting them out until Harrison Butker’s field goal with 1:16 to go. Indianapolis recovered the onside kick without any issue and ran out the clock to celebrate a big win heading into its bye.

Mahomes threw for 321 yards and a touchdown, and the Chiefs (4-1) had just 36 yards rushing despite getting top running back Damien Williams back from an injury, all while watching their record streak of 22 straight games scoring at least 26 points come to a crashing conclusion.

“Penalties are really what hurt us today,” said Chiefs coach Andy Reid, whose team was flagged 11 times for 125 yards. “You get things going, all of a sudden you’re going backward, and it’s tough in this league to do that against a good team and win.”

In an air-it-out era of the NFL, the Colts also won by dominating the line of scrimmage.

On offense, their big line bruised a Kansas City defensive front that lost Chris Jones and Xavier Williams to injuries. That created big holes for Mack and plenty of time for Jacoby Brissett, who threw for 151 yards while running for the Colts’ only touchdown.

On defense, the Colts spent most of the night in the Kansas City backfield, plugging up holes in the running game and relentlessly pressuring the reigning league MVP on passing downs.

Mahomes was sacked four times and hit plenty more. At one point in the second half, Cam Erving was pushed so far into Mahomes’ face that the backup left tackle stepped on his quarterback’s ankle, leaving Mahomes to hobble to the sideline when Kansas City was forced to punt.

“In this league, the margin of error is tiny,” said Mahomes, who dismissed the seriousness of his injury. “If you’re not executing at a high level you’re going to lose.'”

The Colts and Chiefs mostly played to a first-half stalemate, but the second of Vinatieri’s four field goals made it 13-10 at the break. The real winners were the officials, who finally got to rest the arms that they used to throw flags for the first 30 minutes.

The Chiefs’ prolific offense continued to sputter in the second half, and Brissett and the Colts essentially played a game of keep-away throughout the third quarter and into the fourth.

“You don’t need a large playbook to convert third-and-1,” Chiefs defensive end Frank Clark said.

The Colts used 8:34 off the clock to move a mere 35 yards and set up Vinatieri’s next field goal. Then, when the Chiefs failed to convert fourth-and-1 at their own 34, Indianapolis got another field goal from Vinatieri with 2:30 to go to make it a two-possession game.

“You could just tell they were hungry. They were hungry all week,” Reich said. “I know that’s not uncommon, but there was something different about this week. I could feel it. It was palpable. We just walked in here with a lot of confidence. Last night in our meetings, I can’t even explain what happened in our meetings last night. There was just a feeling amongst the team when we walked into this stadium.”

ALMOST INT

Mahomes nearly threw his first interception of the season in the third quarter, when FB Anthony Sherman batted a pass and LB Bobby Okereke caught it. A review showed the ball bounced off the ground.

RING OF HONOR

The Chiefs inducted OL Brian Waters into their Hall of Fame during halftime. Waters was a two-time All-Pro for Kansas City before wrapping his 13-year career with the Patriots and Cowboys.

HAPPY RETURNS

Colts DE Justin Houston celebrated his first trip to Kansas City as a visitor by sacking Mahomes in the first half. The four-time Pro Bowl pick had 78 1/2 sacks during eight seasons with the Chiefs.

FLAG DAY

Chiefs CB Bashaud Breeland had a night to forget. Not only did he struggle in pass coverage, he was flagged four times for 68 yards. That included a 53-yard pass interference call.

INJURIES

Colts: CBs Shak Taylor (chest) and Kenny Moore II (knee) left in the first half, joining inactive safeties Malik Hooker (knee), Glayton Geathers (concussion) and Rolan Milligan (knee) on the Indianapolis sideline. LB Zaire Franklin (hamstring) and DE Kemoko Turay (ankle) left in the second half.

Chiefs: WR Sammy Watkins (hamstring), LB Anthony Hitchens (groin) and DT Xavier Williams (ankle) left in the first half. DT Chris Jones (groin) and LG Andrew Wylie (ankle) left in the second half.

UP NEXT

Colts get the week off before traveling to Houston on Oct. 20.

Chiefs welcome the Texans to Arrowhead Stadium next Sunday.