LOUISVILLE, Ky. — They sat tucked away in the confines of Barn 42 on the Churchill Downs backside, the small plain-looking chestnut gelding and the guy hobbling around on crutches.

With Sheikh Mohammed's regal contenders just next door and trainer Larry Jones steps away, Mine That Bird and his trainer Bennie "Chip" Woolley Jr. weren't exactly inundated with visitors in the days leading up to the 135th Kentucky Derby.

Of all the horses in the field for the first leg of the Triple Crown, the one who was previously winless in the United States was among the least inquired about.

But when the first Saturday in May had concluded, the gelding few had bothered to think about had become all anybody could talk about.

In one amazing, rail-skimming move, 50-to-1 shot Mine That Bird managed to snatch the breath from 153,563 in attendance and countless others when he overtook multiple Grade I winner Pioneerof the Nile in the stretch to win the Kentucky Derby by a widening 6-plus lengths on Saturday.

Only Donerail, a winner at odds of 91-1 in 1913, was a bigger Derby surprise.

While the Derby has seen its share of stunners, this shocker ranks with the most unfathomable.

Though Mine That Bird was Canada's champion 2-year-old male of 2008, the son of Birdstone was winless in two starts this year including a fourth-place finish in the Sunland Derby on March 29.

In his only previous try against Grade I company, Mine That Bird finished last in a field of 12 in the Breeders' Cup Juvenile at Santa Anita Park in October.

But when facing some of the best of his generation Saturday, Mine That Bird notched the largest margin of victory since Assault won by 8 lengths in 1946.

"It's wonderful, it just hasn't sunk in yet," said Woolley, who broke his leg in a motorcycle accident two months ago but still vanned Mine That Bird to Churchill Downs himself in a 21-hour trip from New Mexico. "To be honest I didn't have any real feeling I could win the Derby. We wanted to be competitive. We knew we would be more competitive than everybody gave us credit for."

Mine That Bird showed ability as a juvenile, winning the Grade III Gray Stakes at Woodbine in Canada for his previous trainer David Cotey.

After that effort owners Mark Allen and Dr. Leonard Blach bought him privately for $400,000. Despite a subsequent poor run at the Breeders' Cup, they knew the talent was there.

The wave of good fortune that carried Mine That Bird to his triumph began in March.

Jockey Calvin Borel, who guided Street Sense to victory in the 2007 Kentucky Derby, was the regular rider of graded stakes winner Beethoven earlier this year, but he found himself without a Derby mount when the colt got injured and knocked off the trail in late March.

When the decision was made to send Mine That Bird to the Derby, Woolley was stunned to find Borel available.

"For this horse, he is a perfect, perfect fit," said Woolley, who had had only 173 wins in his career since 1991 and had never saddled a graded stakes winner until Saturday.

Known for his ground-saving ability, Borel proved to be just what Mine That Bird needed in the 1 1/4-mile test.

After they were squeezed at the start, Borel took the gelding to the back of the 19-horse field as pacesetter Join in the Dance set fractions of :22.98 and :47.23 with UAE Derby winner Regal Ransom just off his flank and eventual runner-up Pioneerof the Nile in the three-wide path third.

"My heart sank a little bit when he came by there last but I was really glad to see him that far in front when he came around the second time," Blach said.

As Join in the Dance reached the final turn, Pioneerof the Nile began putting in his bid on the outside and looked to be in winning form as they reached the stretch.

However, in a move reminiscent of his ride on Street Sense, Borel began picking up horses about 3 furlongs out. When a hole opened up along the rail, the rider urged Mine That Bird through the opening and they sailed to the front by midstretch.

"I rode him like he was a good horse," said Borel, who also guided Rachel Alexandra to victory in the Kentucky Oaks Friday to become the first jockey since Jerry Bailey in 1993 to pull off the double. "When he got out of the bit around the three-eighths, I didn't think I would win maybe, but I knew he would come running.

"He's such a small horse he really just skipped across the track. He started picking them up so easy and it was unbelievable."

With Borel waving his whip in celebration in the final strides, Mine That Bird hit the wire in 2:02.66 over a track rated sloppy.

Pioneerof the Nile, who was making his first start on dirt, held gamely to edge out Musket Man by a nose for second with Papa Clem a head back in fourth.

"He was really good," said Garrett Gomez, jockey of Pioneerof the Nile. "When I asked him turning for home he gave me some and stayed on. I looked down and saw (Mine That Bird) coming but he went through there so fast."

Louisiana Derby winner Friesan Fire went off as the 7-2 favorite after morning-line pick I Want Revenge had to be scratched the morning of the race. But Friesan Fire grabbed his left front foot leaving the gate and finished next to last in the 19-horse field.

"If you see blood on the track, it's his," said Jones, trainer of Friesan Fire.

As his connections will attest, few cared to know much about Mine That Bird before Saturday.

By the time the Preakness rolls around in two weeks, they have a feeling the racing community will know a lot more about their underdog gelding.

"This just shows what can be done with two buddies who have fun together and like to go to the races and dream a little bit," Blach said.