MIAMI — Peyton Manning spent the whole season building toward a Super Bowl crown, a win that certainly would put him among the greatest quarterbacks in NFL history.

And then he threw it all away.

Blocked onto his butt, Manning could only watch as Tracy Porter returned an interception for a clinching, 74-yard touchdown in the final minutes Sunday that gave the New Orleans Saints a 31-17 victory over the Indianapolis Colts.

“It’s certainly disappointing. Very disappointed. Disappointed,” Manning said.

It was a startling end to a Super Bowl that seemed destined to wind up in Manning’s strong right hand. It was the lone turnover of a back-and-forth thriller — who in the world would have thought the big mistake could be made by Manning?

Yet there he was, sitting on the grass after brawny Saints defensive end Will Smith knocked him down as he tried to make a tackle. Manning took a glance over his shoulder to watch Porter’s romp to the end zone, unbuckled his chin strap, stood up and simply walked toward the bench.

“We probably never got into a great rhythm. We were certainly worse in lapses in our final possession,” Manning said.

All week, this was the story line in Miami: Could Manning, a New Orleans boy through and through, deny the Saints in a game they desperately wanted to win for their city?

Turned out he helped his hometown team win its first Super Bowl — only not in the way he imagined.

Dad Archie Manning, the longtime star Saints quarterback, got caught smack in the middle.

“I was pulling for the Colts. I’m not quite over that, but I’m happy for New Orleans,” he said.

“I don’t know if I’m going to celebrate or not. Maybe later, when the city does, but I’m not in a celebrating mood. Glad to see everybody else in New Orleans celebrate. That’s enough for me now,” he said.

Added Archie: “I’m proud of him. … It just wasn’t meant to be.”

His son repeated the word “disappointing” at least 10 times in his postgame interview session, using it to describe everything from the Colts not having the ball much in the second quarter to the interception that decided the title.

“We played well in the first playoff game, played well two weeks ago. We just didn’t make enough plays against the Saints,” Manning said.

“I understand how excited the Saints are, their families and the city of New Orleans is going to be,” he said. “I’m sorry to our fans that we weren’t able to get it done.”