KANSAS CITY, Mo. — Bill Belichick has made a career out of chewing up young quarterbacks and spitting them out, checkmating them in a game of football chess.

But Patrick Mahomes (16-for-31, 295 yards, 3 TDs) awoke with a vengeance in the second half and scared the hell out of Belichick before Tom Brady got him and his coach to their ninth Super Bowl with the overtime drive that subdued Mahomes and the Chiefs, 37-31.

Mahomes, under duress, had been shut out in the first half before battling Brady tooth and nail with a clutch drive for a field goal in the final minute and a 24-point fourth quarter.

Mahomes, at the end of a remarkable MVP season, took it hard.

“It hurts. It hurts everybody,” Mahomes said. “We know this can be a building block. It could be something that carries us in the future. Right now it’s the end but hopefully it’s the beginning of a long time.”

“He’s hurting,” coach Andy Reid said. “He’s a competitive kid, so he’s emotional right now. He will get through that. He’ll grow from this. He knows that. It’s not easy right this minute.”

The kid gives the town hope for a bright future.

Just no more present. No Super Bowl against the Rams.

But you can’t take your eyes off him.

Daniel Sorensen had intercepted a Brady pass off Julian Edelman’s hands and Mahomes had it at the Patriots’ 23. Mahomes rolled right, stopped, looked to his left for Damien Williams, and it was Chiefs 21, Patriots 17.

Mahomes ran to the Chiefs sideline for a body bump and exulted.

He had found Sammy Watkins for 10 yards on third-and-3 just before Adrian Claiborne plastered him into the ground, then Williams out of the backfield wide open down the right sideline for 33 yards. They started chanting “MVP” when he hit Williams past Dont’a Hightower with the 1-yard TD pass that made it Patriots 17, Chiefs 14, 14:51 remaining.

Mahomes had awakened at the start of the second half. He scrambled right and uncorked a long-range missile to Watkins for 54 yards, then hit Travis Kelce with the 12-yard TD that cut his deficit to 14-7.

Kelce finished with three catches for 23 yards. Tyreek Hill had 1 for 42. “They doubled him on like 95 percent of the plays,” Mahomes said.

Belichick took them away and forced Mahomes to try to beat him with Sammy Watkins (4/114) and Damien Williams (5/66 and 2 TDs). And he almost did.

“We just have to find ways to start better,” Mahomes said.