LEXINGTON, Ky. - Horse of the Year and two-time champion Alysheba has died just five months after returning to Kentucky from Saudi Arabia, where he stood eight years at stud for Saudi King Abdullah.\nThe 25-year-old classic winner fell in his stall Friday afternoon at the Kentucky Horse Park's Hall of Champions in Lexington, injured a leg, and had to be euthanized. Horse Park staff called Dr. Nathan Slovis of the nearby Hagyard Equine Medical Institute, and because Alysheba was unable to stand, Slovis and his veterinary team transported him by ambulance across Iron Works Pike to Hagyard for evaluation and treatment. \n"Due to a chronic degenerative spinal condition that led to ataxia [lack of coordination] and instability, Alysheba fell in his stall yesterday, injuring his right hind femur," the park's director of equine operations, Kathy Hopkins, said in a statement the park issued Saturday. "Complicated by his advanced age, this trauma resulted in severe pain that did not respond to analgesic therapy. The resulting pain and suffering, and the inability to stand unaided, led to a joint decision for euthanasia. This very difficult decision was made by the veterinary staff of Hagyard Medical, the veterinary staff of His Majesty King Abdullah, and those who loved and cared for him at the Kentucky Horse Park."\nAlysheba was euthanized at Hagyard at 11:13 p.m. and was buried Saturday morning outside the Hall of Champions, across from John Henry's grave. He had lived his last few months in John Henry's former stall and paddock.\nAlysheba, a son of Alydar and the Lt. Stevens mare Bel Sheba, won the 1987 Kentucky Derby and Preakness as well as the Super Derby en route to his divisional championship as the season's top 3-year-old male. He finished second, a nose behind 1986 Derby winner Ferdinand, in the 1987 Breeders' Cup Classic. But the following year, at 4, he ended his career with a half-length victory over Seeking the Gold in the Classic to clinch the 1988 Horse of the Year title and champion handicap horse honors. In his career, Alysheba won 10 stakes, nine of them Grade 1. \nPreston Madden bred Alysheba and sold him for $500,000 to Dorothy and Pamela Scharbauer at the 1985 Keeneland July select yearling sale. Hall of Famer Jack Van Berg trained Alysheba. The horse retired in 1988 as the world's richest Thoroughbred, with earnings of $6,679,242. He held that distinction until fellow Hall of Fame resident, 1995 and 1996 Horse of the Year Cigar, surpassed his earnings.\nKing Abdullah, who stood the stallion at his Janadria Farm, announced last October that he would return Alysheba to Kentucky as a gift to the horse's legion of fans. Alysheba's Oct. 31 welcome party at the Hall of Champions drew several hundred fans who hailed the event as a return home for "America's Horse."