The Patriots' secondary has been hobbled by injuries. Two starters, safety Devin McCourty and cornerback Alfonzo Dennard, missed the 34-20 win over the Buffalo Bills that ended the regular season. And cornerbacks Aqib Talib and Kyle Arrington have been playing hurt.
But the bye week gave them time to heal and a better chance to stop Luck.
He completed 29 of 45 passes for 443 yards, four touchdowns and three interceptions against the Chiefs. His 64-yard scoring pass to T.Y. Hilton with 4:21 left capped the comeback. Hilton's 13 catches for 224 yards broke franchise playoff records.
"He's, as we saw, a go-to guy," Belichick said. "He had a couple hundred yards yesterday, but he's shown up all year. He's a big key to it, but Luck has done a good job spreading the ball around. He's made some key throws to a lot of guys."
Saturday's game will be the fourth in the playoffs between the teams. In the most recent meeting, the Colts made another impressive comeback. With Peyton Manning at quarterback seven years ago, they won the AFC championship game 38-34 after trailing the Patriots 21-6 at halftime.
But that game was in Indianapolis.
Saturday's will be in Foxborough where the Patriots are 8-0 this season but lost last year's AFC title game to the Baltimore Ravens 28-13.
New England goes into Saturday's game with five wins in six games. Indianapolis has won its past four.
"For the most part this year, they've played mistake-free and have an explosive, well-balanced attack," Belichick said, "Obviously, Luck has done a great job and they have a tremendous passing game, but their balance, their running game, their offensive line, production out of their tight ends, has been solid, too."