Shackleford, the 2011 Preakness winner, ended his career with a victory Friday in the 138th running of the Grade 1 Clark Handicap at Churchill Downs.
Ridden by Jesus Castanon, Shackleford broke sharply and led throughout to beat Take Charge Indy by a length, running 1-1/8 miles in 1 minute, 49.12 seconds.
Sent off as the second choice in the field of nine, Shackleford paid $7.80 on a $2 win bet.
Bourbon Courage was third.
The $266,054 winner's share pushed Shackleford's career earnings to $3,090,101. It was the third Grade 1 victory in 20 career starts for the Dale Romans trainee owned by Mike Lauffer and Bill Cubbedge.
A troubled seventh in his last start, the Breeders' Cup Mile at Santa Anita, Shackleford will now stand stud at Darby Dan Farm in Lexington.
''That's the way he's supposed to leave,'' Romans said. ''That's Shack at his best. That's how we expected him to run in the Breeders' Cup and it wasn't his fault that he stumbled.''
The Clark was a reunion for Shackleford and Castanon, who teamed up for last year's Preakness score. Castanon last rode the 4-year-old chestnut son of Foresty to victory in the Churchill Downs Handicap by a nose on this year's Kentucky Derby undercard, but broke his hand in a spill 13 days later.
''It was very emotional,'' Castanon said about his return ride. ''When I spoke to Dale and he told me I would be back on him, I was so happy. To be able to ride him in his last race was amazing.''
After a quick exit from the gate, Shackleford settled into a moderate pace, covering the first half mile in48.65 seconds.
''When they went 48, I thought it was going to be tough to get by him. When he came off the turn, you could tell he was in cruise control,'' Romans said. ''He was a man against boys at that point.''
After finishing fourth while setting the pace in last year's Derby, Shackleford returned in the Preakness to give Castanon and Romans their first classic win. Romans chose to keep Shackleford at home for his finale in the Clark rather than ship to New York for the Cigar Mile at Aqueduct and the Louisville native was also nostalgic following Friday's win.
''It's the end of an era for my stable,'' Romans said. ''He took my career to a new level. He made my resume totally different than it was before he came into the barn. I owe him a lot.''
Romans also conditions Shackleford's older half-sister, Afleeting Lady, who won Thursday's Grade 2 Falls City Handicap. The Clark is the ninth Grade 1 win in a banner year for Romans that marks him a leading contender for this year's Eclipse Award given to the nation's top trainer. In addition to Shackleford's May 28 win in Belmont's Metropolitan Mile, Romans collected some of the country's most prestigious races including Keeneland's Blue Grass, the Arlington Million and the Breeders' Cup Turf.
