INDIANAPOLIS -- When the final seconds were ticking away, as Indianapolis Colts quarterback Andrew Luck glanced behind him to find running back Donald Brown grinning as the offense prepared to kneel in victory formation, it was apparent how much the Colts had grown up. This wasn't merely about a miraculous comeback in one of the wildest playoff games in recent memory. It was about a team taking the next step in a journey that started last season, with an ailing coach and a legend in the franchise's rearview mirror. When the Colts look back on whatever happens during the Luck era, they will remember this night as square one of their true maturation.

Even now, it's still difficult to explain exactly how Indianapolis overcame a 28-point deficit to earn a 45-44 AFC wild-card win Saturday over the Kansas City Chiefs. There were key defensive stops here, big pass plays there and a fortunate bounce on a Brown fumble that Luck nabbed and turned into a 5-yard touchdown. More than anything, the young Colts played like it didn't matter if they'd spotted their opponent a four-touchdown lead early in the second half. The Colts couldn't be fazed. They believed in their chances as long as time remained on the clock.

This isn't something that happens easily, by the way. It takes years for most teams to develop such a combination of resilience and resourcefulness, and the Colts already have it mastered in the two since their former star quarterback, Peyton Manning, left town.

"This team has never panicked since I've been a part of this club," Luck said after the game. "Guys just play football. We knew there was no 28-point score. Guys just stepped up."

As simple as Luck made it sound, that really is how the Colts came back. They kept plugging away, kept pushing the ball downfield, kept pounding the Chiefs whenever they had a chance to steal a little more momentum in their favor. It's an attitude that surely evolved last season, when the Colts were written off the minute Manning moved on and Luck stepped into a colossal rebuilding project. There was seemingly no way a team that picked first in the draft in 2012 -- a franchise that basically had cleaned house, with head coach Jim Caldwell and general manager Bill Polian also tossed out the door -- could grow up so fast.

Then Luck started proving why he was so celebrated when he became the first overall draft selection. The team also showed its heart in the way it rallied around head coach Chuck Pagano, who was sidelined for three months last season as he battled leukemia. "Chuckstrong" became the movement that united a team and ignited a city. It also proved to have a lasting effect on a Colts squad that really understands that legitimate pressure is about life and death.

Colts defensive end Cory Redding and head coach Chuck Pagano celebrate after Indianapolis produced one of the greatest comebacks in league history. Brian Spurlock/USA TODAY Sports

The only way to make sense of what happened Saturday is to realize that Indianapolis plays best when people expect the worst. Many people believed this team would take a step back this year after finishing 11-5 in 2012 and losing the emotional motivation that Pagano's illness inspired. Instead, the Colts wound up 11-5 again. They also claimed the AFC South title. They also beat Denver, San Francisco and Seattle, three teams that most people would argue have the best chance of winning this year's Super Bowl.

Sure, the Colts produced a few stinkers -- including blowout losses to St. Louis, Arizona and Cincinnati -- but those now seem more like the obvious curse of youth. They were letdown games, moments when a blossoming team forgot that any opponent can embarrass you if you're not ready to play. Given how Pagano has handled this squad, the Colts learned their lessons fast. They weren't good enough to thrive without giving their best effort every time out.

Saturday's game felt very much like some of those disappointments early. Most of that also had to do with how the Chiefs were playing instead of the Colts not showing up. Even with star running back Jamaal Charles suffering a concussion on the first possession of the game, Kansas City executed a game plan that was almost flawless. The Chiefs forced Luck into three interceptions, connected on long passes to wide receivers Dwayne Bowe and Donnie Avery and rallied behind the brilliance of quarterback Alex Smith, who threw for 378 yards and four touchdowns. The Chiefs had never looked better all season.

That, in the end, might have been their biggest problem. That effort actually put the Colts into a comfort zone, and Pagano played on that at halftime.

"We've been here before," said Pagano, adding that he told his team to "trust techniques, fundamentals. I know I sounded like a broken record, but that's what we did. We did it one play at a time."

Da'Rick Rogers gives T.Y. Hilton a boost, but it was Hilton who lifted the Colts with 13 catches for 224 yards and a pair of touchdowns. Brian Spurlock/USA TODAY Sports

It's fair to say the Colts needed every big play they created to win this game. It didn't seem that huge when Pro Bowl outside linebacker Robert Mathis sacked Smith and forced a fumble that linebacker Kelvin Sheppard recovered early in the third quarter. But as it turned out, the game pivoted on that turnover. Luck also engineered three scoring drives in that same quarter, none of which lasted longer than two minutes. The speed of those possessions was equally crucial to the comeback.

Of course, the dagger was a 64-yard touchdown pass from Luck to wide receiver T.Y. Hilton -- who finished with 13 receptions, 224 yards and two touchdowns -- with 4 minutes, 21 seconds remaining in the game. The Chiefs will spend months trying to understand how a second-year receiver could dominate them. They might need even more time to decipher how Hilton raced past two safeties to grab the game-winning toss when the smart money had Luck looking for him in a pinch. What the Chiefs should do is simply accept that they were dealing with Indianapolis at the worst possible time, with the Colts' backs up against the wall.

In truth, it was difficult to see Indianapolis doing this before Saturday's game. The Colts seemed like an inconsistent squad trying to find itself, one blessed with the good fortune to play in a division where a potential Super Bowl contender, the Houston Texans, shockingly imploded this season. Luck was on a path to elite status but the star power was sidetracked when Pro Bowl wide receiver Reggie Wayne was lost for the season with a torn ACL. The Colts were a nice little story, at best.

Now it's worth taking them far more seriously as the next round of the postseason nears. As Pagano said in the postgame news conference, "You can measure a lot of things at the combine, but you can't measure heart."

Even tougher to gauge is how much adversity helps a team grow up. Last season, the Colts revealed that they could band together for the good of their leader. On Saturday, they proved something else -- that the lessons they learned during that traumatic year are still very much a part of this team's magic.