And it was 24-1 long shot Ruler On Ice who delivered a huge upset yesterday in the final leg of the Triple Crown, splashing his way to a three-quarter-length victory over Stay Thirsty.

As expected, Shackleford led from the start but when the field of 12 turned for home in the 1 1/2-mile Belmont, he tired in the muck as long shots Stay Thirsty and Ruler On Ice passed him by.

“Ruler wasn’t slowing down,’’ said winning jockey Jose Valdivia Jr. “It was a great feeling the last 16th of a mile.’’

The much-hyped rubber match between Shackleford and Kentucky Derby winner Animal Kingdom never developed on a rainy day at Belmont Park. Shackleford finished fifth, while Animal Kingdom got off to a terrible start, never moved into contention, and finished sixth.

Jockey John Velazquez nearly fell off when Animal Kingdom collided with Monzon just after the start. He somehow managed to get his left foot back into the stirrup, but by then it was too late. Animal Kingdom had dropped more than 12 lengths off the lead, and did well to finish in the middle of the pack.

An elated Valdivia, riding in his first Belmont, described the final seconds of the race while still on his horse.

“I’m a couple of yards from the wire and I’m thinking, ‘Oh my god, oh my god, I’m going to win the Belmont,’ ’’ he said.

A crowd of 55,779 turned out hoping to see a stretch showdown between Animal Kingdom and Shackleford. But that vanished once the Derby winner was knocked out of contention in a bad bit of racing luck.

The Belmont has a history of surprise finishes, from spoiled Triple Crown attempts to stunning shockers. Only two favorites have won since Thunder Gulch in 1995, and long shots have been the norm. Last year, it was 13-1 Drosselmeyer, two years ago Summer Bird at 11-1, and three years ago Da’ Tara at 38-1.

Birdstone spoiled Smarty Jones’s bid for a Triple Crown in 2004 at 36-1 and Sarava ended War Emblem’s Triple try in 2002 at 70-1.

The win left Lori Hall, who owns Ruler On Ice with her husband George, shaking.

“It was amazing, because we really were the underdog,’’ she said.

Ruler On Ice’s victory makes it three years in a row a different horse has won each of the Triple Crown races, and next year it will be a 33-year gap since Affirmed swept the Derby, Preakness, and Belmont in 1978.

Ruler On Ice, trained by New Jersey-based Kelly Breen, did not run in the first two legs of the Triple Crown. The 3-year-old gelding didn’t have enough graded stakes earnings to qualify for the Derby, but vindicated his trainer’s faith by defeating a field that included the first seven finishers in the Run for the Roses.

The winning time for the oldest and longest race in the Triple Crown was a slow 2:30.88.

Ruler On Ice, a temperamental sort fitted with blinkers for the first time to keep him focused, returned $51.50, $26, and $13.60. Stay Thirsty, owner Mike Repole’s second-best 3-year-old behind the sidelined Uncle Mo, paid $19.40 and $10.80. Brilliant Speed was third and returned $7.90 to show.

Nehro, second in his last three races, including the Derby, was fourth, followed by Shackleford, Animal Kingdom, Mucho Macho Man, Santiva, Monzon, Master of Hounds, Prime Cut, and Isn’t He Perfect.