It was the moment of truth Ahmad Bradshaw had dreamed of since he was a kid hearing play-by-play commentary inside his head. With his team trailing and a minute left in the game, it was his chance to score the winning touchdown in the Super Bowl.

So the New York Giants running back took the handoff from Eli Manning and dashed into a remarkably unobstructed pathway. It was like he was standing in a security line at the airport and everybody in front of him moved aside with a chorus of “you first.” Why was 500-pound Vince Wilfork all but whisking him along instead of trying to smush him like an ant? Bradshaw saw a red carpet to the end zone.

Then Bradshaw heard Manning behind him yelling, “Don’t score! Don’t score!”

At the 2-yard line, Bradshaw slammed on the brakes. “Screech!” He was the driver in a chase scene trying to skid to a stop before his car went over the lip of a rising drawbridge.

At the threshold, he hesitated, put a hand down on the grass and began to kneel. But he could not break the laws of physics. He spun, squatted and fell into the end zone, landing squarely on his buttocks.

The first “tushdown” he had ever seen, said Billy Crystal on Twitter.

The Giants’ 21-17 victory over the New England Patriots in Sunday’s Super Bowl XLVI was full of highlights, but the most memorable moment, next to Mario Manningham’s balletic sideline catch, was Bradshaw trying, against every instinct, not to score. Legs trained to go forward were suddenly told to go in reverse.

Unwanted TD

Bradshaw’s 6-yard run will be replayed as the accidental touchdown, the inadvertent touchdown, the unwanted touchdown.

“He wanted to stop!” exclaimed broadcaster Al Michaels. “That’s exactly what New England was doing, they were letting him get into the end zone.”

Said Michaels’ partner, Cris Collinsworth: “A big mistake.”

In a fascinating bit of endgame strategy, the Patriots — who were winning — allowed Bradshaw to score so they could get the football back with 57 seconds remaining, maybe enough time for Tom Brady to work the same kind of last-minute magic that Manning had conjured when the Giants beat the Patriots in the 2008 Super Bowl and now again in 2012.

The Giants — who were losing — tried to prevent Bradshaw from scoring so they could bleed the clock, force the Patriots to use a timeout, kick an easy field goal and leave Brady with 12 seconds or so to heave a miracle.

As it happened, Brady had nearly a minute and the game came down to the last play, a Hail Mary jump ball that Aaron Hernandez and Rob Gronkowski both had a shot at catching.

“I was nervous because they are a great team, and you don’t want to put the ball in Brady’s hands,” Bradshaw told reporters after the game. “I was so anxious. I was nervous. I was shaking. It was scary. But our defense held up.”

A strange way to feel after scoring the go-ahead touchdown. When Brady’s pass fell incomplete, Bradshaw collapsed on the sideline, relieved that his gaffe was a gift.

A big Super Bowl

Between Madonna’s halftime extravaganza, the $3.5 million commercials and the tense ending, it was an over-the-top Super Bowl.

If Brady had made a winning pass, Bradshaw would have been the Super Bowl XLVI goat who gave him too much time. If the Giants had opted for a field goal and missed, Bradshaw would have been blamed for not scoring a sure thing. But had the Giants nailed a field goal for an 18-17 lead with a little time still left, Brady would have only had to bomb it within field-goal range — and he’s the quarterback who has led two game-winning field goal drives in Super Bowls. Bradshaw’s touchdown forced the Patriots to get a touchdown.

Patriots coach Bill Belichick didn’t want to wait to see if the Giants messed up a short field goal because he figured 90 percent of the time that wouldn’t happen. Bradshaw made the first part of Belichick’s gamble pay off even though Giants offensive coordinator Kevin Gilbride said Bradshaw had “rehearsed those situations. He did sit himself down, but they didn’t give it to him.”

The replay will be on the list with all the bizarre ones, including David Tyree’s helmet catch, Garo Yepremian’s pass and Franco Harris’ deflection reception.

TD of a lifetime

“At the Giants, we want touchdowns, that is always on your mind,” Bradshaw said. “It goes against your nature to not score when you spend your whole life trying to score. Even though Eli was telling me, it only clicked when I was at the 1-yard line. Usually when you tap down, you can declare yourself down, but they didn’t blow the whistle.”

And so, the touchdown Bradshaw didn’t really want to score turned out to be the biggest of his life.

“That could be the best run of my career,” Bradshaw said. “And there wasn’t even anybody trying to stop me.”