“He seen it in some guys’ eyes, they were getting down, including myself,” said receiver Tyreek Hill, whose 44-yard reception on third-and-15 from the Chiefs’ 35-yard line propelled the comeback. “I was like, ‘Man, how are we going to pull this off?’ And he was like: ’10, you’ve got to believe, brother. Like the same faith you’ve had all of your career, you’ve got to believe right now. It’s going to happen, man. I can feel it.’ He brought the guys together, and you saw what happened.”

What happened was another instance of Mahomes’s demonstrating how normal rules do not seem to apply to him. The same quarterback who missed only two games with a dislocated kneecap, who flicks passes with his off hand or without looking, shredded what by some metrics was the N.F.L.’s best pass defense in the last 10 years.

During the regular season, San Francisco allowed 169.2 passing yards per game, the fewest in the league since 2009. Mahomes, selected as the game’s most valuable player, nearly matched that total in the fourth quarter, when he threw for 141 yards and two touchdowns, to Travis Kelce and Damien Williams. Five times this season the Chiefs have trailed by at least 10 points, and all five times they won.

“Doesn’t matter what the score is,” Kelce said. “We’ve got Pat Mahomes. We’ve got an unbelievable defense and they’ll put their foot in the ground against anybody.”