Kentucky Derby winner Big Brown has been retired after sustaining a foot injury during a turf workout at Aqueduct Racetrack in Jamaica, N.Y., ending any hope of a showdown between Big Brown and reining Horse of the Year Curlin in the $5 million Breeders' Cup Classic.

Big Brown had worked a sparkling six furlongs in 1:12 4/5 with stablemate Kip Deville, the defending Breeders' Cup Mile winner. But in the process, his hind foot knocked flesh off the inside of his right front foot.

"He not only tore the bulb off his foot, but half the foot was torn off," bloodhorse.com quoted IEAH Stables co-chairman Mike Iavarone as saying. "We did everything we could to get to the Breeders' Cup. It's devastating. And what makes it even worse is that he worked great."

The National Thoroughbred Racing Association scheduled a teleconference call with Iavarone for 2 p.m. Monday.

When asked if Big Brown was retired, Three Chimneys Farm in Versailles, Ky., where Big Brown is scheduled to stand at stud next year, referred a reporter to Iavarone's comments on the Blood-Horse Web site.

In a brief phone conversation, trainer Rick Dutrow did not go into the extent of the injury, saying, "He's got a foot issue. He's going to miss the race, period."

When asked if Big Brown might race again before retirement, perhaps in a race such as Churchill Downs' Clark Handicap, Dutrow said, "I'm not searching for another spot for him. I don't know what the position would be with the farm."

Big Brown has been plagued by foot problems, racing in special glue-on shoes and developing a quarter crack two weeks before the Belmont Stakes. He sustained his only defeat in the Belmont, finishing last.

While there were many theories about what happened that day, his camp has never blamed the foot, which was repaired with a high-tech patch.

Big Brown's defection is a major blow to the Breeders' Cup, which will be Oct. 24-25 at Santa Anita Park in Arcadia, Calif. For the first time, the event is being held on a synthetic surface and will have 14 races over the two days.

Meanwhile, the Curlin camp hasn't entirely committed to running. The 4-year-old colt was shipped to Santa Anita the day after he won New York's Jockey Club Gold Cup in order to see how he liked the new Pro-Ride surface. He was set to have a major workout in between races at Santa Anita Monday afternoon .

One criticism of synthetic surfaces is that they can be different in the morning than the afternoon.

Horses must be pre-entered by noon Tuesday in order to compete in the Breeders' Cup. The complete list of pre-entrants is set to be made public Thursday afternoon.