Alydar suffered a fractured cannon bone in his right hind leg late Tuesday when he kicked his stall door at Calumet Farm in Lexington, Ky., where he had been a stallion since 1979. He underwent two hours of surgery Wednesday for what one veterinarian called a "terrible fracture" that required a small steel plate, five pins and a fiberglass cast.

Shortly after the cast was removed yesterday morning, Alydar fell and suffered another fracture of the injured leg. He was put down at 8:30 a.m. and buried at Calumet.

"Everything went so well {Wednesday} that we were optimistic we could get him through," said Larry Bramlage, who performed the surgery with William Baker. "He began resenting the sling . . . and was tranquilized. Today {Thursday}, it was either maintain him in a tranquilized state -- and he was starting to show signs of colic -- or wean him out of his sling. Fifteen minutes after it was off, he slipped and fell."

Few horses were as celebrated in defeat as Alydar. After losing the 2-year-old horse of the year title to Affirmed in 1977, he chased his nemesis through the Kentucky Derby, Preakness and Belmont the following year, but couldn't get past him. Affirmed won the Derby by 1 1/2 lengths, the Preakness by a neck and the Belmont by a head, the two running side by side for about a mile.

A son of Raise A Native and the mare Sweet Tooth, Alydar won 14 of 26 starts and $957,195 for Calumet Farm and trainer John Veitch. He was second nine times.

Alydar sired Alysheba, 1988 horse of the year, and Eclipse Award-winners Easy Goer, Turkoman and Althea.