KANSAS CITY, Mo. — An hour after her 23-year-old son had demolished the Indianapolis Colts, 31-13, vanquished a quarter century of Kansas City Chiefs playoff futility at home and announced the postseason arrival of a new championship quarterback threat in the AFC, Randi Martin stood in a crowded Arrowhead Stadium elevator and shook her head at the wonder of it all.

“I was watching him doing the interviews and interacting with all those people,” she said. “I was just amazed. I don’t know how he does it.”

It’s something all the Chiefs and most of football must have been wondering as Patrick Mahomes stormed through the regular season with 5.097 passing yards and 50 touchdown passes. In just his second NFL season and his first as a starter, he would have to take a Chiefs team that came in having lost 10 of its past 11 playoff games and somehow pull it to an elusive conference championship game next Sunday.

On a cold Saturday, with snowflakes dancing through Arrowhead Stadium, Mahomes did all of that in the Chiefs’ thumping of the Colts. On a day when many wondered if the pressure of a playoff game would be too much for someone so young, Mahomes ran the Chiefs offense like a veteran, drawing the Colts into several offsides penalties and bewildering their defense with a series of shouts and gestures.

He only threw for 278 yards, didn’t have a touchdown pass and his 85.2 passer rating was almost pedestrian compared to some of his more outrageous performances. But later, what impressed the Chiefs players and coaches as much as Mahomes’s mother is the fact he led Kansas City to a playoff win. And that was more important than all the big touchdown throws of the regular season.

“He does a very nice job with the snap count,” Chiefs Coach Andy Reid said with a small smirk. “He’s got a knack for [drawing defenders offsides] he’s got that special voice.”

Later, as Mahomes sat on a stool in the locker room, slowly pulling on his clothes, his center Mitch Morse, glanced across the locker room and shook his head.

“The guy’s just built different,” he said of Mahomes. “Just the way the guy’s life has changed in the last few months. So much has happened in his life. He can’t even walk down the street anymore without being mobbed.”

Or to his locker room. Just to get from the field to his locker, Mahomes had to run through an adoring mob of fans who finally believe they have the quarterback to take them to a place they’ve never been. He jogged past a lounge just outside the locker room that was filled with fans all wearing his No. 15, shouting his name and hoping that a Super Bowl that has eluded them for years might at last be a possibility.

The Chiefs hadn’t won a home playoff game since 1994 and there has been a generation of January frustration here. Saturday seemed to promise another disaster. A steady snow fell all night and through the morning, blanketing the trees, streets and sidewalks in a thick layer of snow — hardly the climate to enable a dynamic offense run by a young quarterback from Texas. Three hours before the game, cars already clogged the snow-filled highways circling Arrowhead. The snow fell so fast that it was almost impossible to see the stadium, with its lights ablaze, from the back of the parking lot.

When Arrowhead’s gates opened, fans in the upper deck found several inches of snow on their seats. A fierce wind batted the flags on top of the scoreboard. You could barely see the hash marks. It seemed to be the wrong afternoon for Patrick Mahomes.

But then not long before kickoff the snow slowed, the clouds hanging over the stadium lifted. The field cleared and Mahomes dazzled. He led Kansas City on three scoring drives, allowing the Chiefs to build a 17-0 lead early in the second quarter then controlled the game, running down clock as a maligned Kansas City defense — ranked last or close-to-last in many key categories, smothered the Colts and quarterback Andrew Luck.

Indianapolis didn’t have a first down until late in the first half and wound up holding onto the ball for just 20:11 — or slightly half the time as the Chiefs. Luck, the experienced star in this game who had led the Colts to five straight wins before Saturday, had just 203 yards passing, was intercepted once and looked rattled.

Mahomes, the one who might have been expected to be overwhelmed, simply maneuvered the Chiefs downfield again and again.

“I’m just proud of the way he goes about his business,” Reid said of his quarterback who looked anything but 23 on Saturday.

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