Street Sense seemed to have the race won after another of his patented rallies, taking the lead in the stretch under the guidance of Calvin Borel. But under a fierce ride by Robby Albarado, Curlin snatched away the victory.
With Street Sense in his sights, Curlin relentlessly narrowed the margin with every stride. Albarado, sensing the Derby winner was his, went into an all-out drive for the finish, furiously whipping the big chestnut colt in one of the most thrilling Preakness finishes in years.
Two races earlier, Albarado was thrown from his mount but walked away unhurt.
Though a horse had to be euthanized in that race, it was the only sad note on a day that crackled with excitement - in stark contrast to the horror of Barbaro's breakdown last year.
The winning time was a blazing 1:53.46, which equaled the stakes record of 1:53 2/5, according to Pimlico officials. Louis Quatorze in 1996 and Tank's Prospect in 1985 won in 1:53 2/5.
It all started with a stumble.
Curlin, who finished third in the Derby, was well back in the field of nine after a slight stumble out of the gate. As Hard Spun swung into the lead with a three-wide move, Street Sense started to roll under Borel.
Street Sense went to the outside in the stretch and moved into the lead, and the record crowd of 121,263 spectators began cheering in anticipation of a Triple Crown bid in the making.
But Curlin came flying along the far outside, and took dead aim at the Derby winner. He caught him on the final jump and, just like that, Street Sense was a beaten horse.
"I thought I had a different horse the first quarter of mile," Albarado said after his first Preakness victory. "He started a 2-year-old and finished a 5-year-old."
Borel, who was so masterful in guiding Street Sense past 19 rivals and a Derby victory by 2 lengths, thought he had another victory when he broke clear of the field.
"I thought I was home free," Borel said. "He came and got me. No excuses."
Carl Nafzger, who trained Street Sense, put it a tad differently.
"Heartbreaking, that's what it was," Nafzger said. "We only needed a nose. Curlin ran a hell of a race, but we had Curlin. We should never have let him come back and get us.
"When you open up a lead and have two lengths of daylight you're supposed to win the horse race. Other horses wouldn't have never tried that last kick like Curlin did."
Curlin, sent off as the 3-1 second choice, returned $8.80, $3.80 and $2.80. Street Sense, the 6-5 favorite, returned $3 and $2.40. Hard Spun was third and paid $3.
The same three horses were the top three in the Derby - Street Sense, Hard Spun and Curlin, who was nearly eight lengths behind the winner.
Curlin, who did not race as a 2-year-old, was purchased after his first race - a 12-length romp at Gulfstream Park in February. The price was a reported $3.5 million by a group that includes Kendall-Jackson Wine owner Jess Jackson.
The big chestnut colt came into the Preakness with just four career starts. Still, trainer Steve Asmussen was confident in his lightly raced colt, and believed the son of Smart Strike would improve after his first defeat.
Did he ever.