The 3-1 favourite Capri, ridden by Ryan Moore, won the St Leger at Doncaster for trainer Aidan O’Brien.
Moore gained his first victory in the world’s oldest Classic as the Irish Derby winner beat runner-up Crystal Ocean and third-placed Stradivarius.
The grey Capri prevailed after a battle down the straight to give O’Brien his fifth triumph in the race.
“He’s a horse with a lot of class and Ryan gave him a great ride,” said the Irish trainer.
O’Brien saddled four in the 11-runner race, considered one of the best renewals in recent years, and his outsider The Anvil set the early pace.
Stradivarius, under James Doyle for four-time winning trainer John Gosden, took the lead with four furlongs to go,
Crystal Ocean also mounted a challenge but Capri had enough left to see off his rivals in the mile and six-furlong contest.
“When Crystal Ocean came to him, he dug in. He’s done very little wrong in his career and has progressed from race to race,” said Moore.
“It was a very good performance in a very good St Leger.”
Asked for his reaction on winning the race for the first time, Moore replied: “It means you have to win it again, really.”
Cornelius Lysaght, BBC racing correspondent
What a tremendous race as Capri was chased through the closing stages by Crystal Ocean and Stradivarius, both their jockeys in dark silks with yellow caps; it was a stirring sight.
Ryan Moore was celebrating his first St Leger at the eighth attempt, but might well have won before, but for Irish Champions Weekend which often clashes.
Not every St Leger over the years has been fantastic in terms of quality, but this was very much on the high side – Moore agreed that those just behind would probably have been good enough to win a ‘normal’ staging.