(Reuters) - Police opened a homicide investigation in Louisville, Kentucky, on Sunday after a man's body was found in a barn behind Churchill Downs, just hours after the Kentucky Derby was run at the track.

Police spokeswoman Alicia Smiley said authorities received a call at about 5 a.m. (0900 GMT) on Sunday reporting a body found in a barn not far from where I'll Have Another, the horse that won Saturday's race, was stabled.

Smiley said the victim was an unidentified Hispanic male.

She said police had determined foul play was involved and were investigating the death as a homicide. The cause of death would be determined by the coroner, she said.

On Saturday, I'll Have Another, ridden by jockey Mario Gutierrez, won the 138th running of the tradition-rich Kentucky Derby at Churchill Downs in a stunning finish before a record crowd of more than 165,000 people.

(Reporting by James B. Kelleher; Editing by Colleen Jenkins and Bill Trott)