John Larkin's Bayross with John Sullivan up, caused a 33/1 surprise in the concluding Mirror (Pro/Am) INH Flat Race at Down Royal.
The 7Ib claiming amateur got the once previously raced son of Karinga Bay up in the closing stages to beat fellow outsider Lady Olwyn by a length and a quarter.
Larkin's wife Amanda said: "He'd been going well at home and we expected a very big run despite his price. He was supposed to run at Wexford and Fairyhouse before those races were abandoned so it's third time lucky.
"We have no plans now and it is great for his owners (the MOCW Syndicate). Derek Williams and Dermot and Pat O'Callaghan from Dundalk own him and he is their first horse. He was bought at the Derby Sale."
