A 300-1 shot won the fourth race of the day at Leopardstown on Thursday.
He Knows No Fear got up on the line to beat evens favourite Agitare to the victory in the one mile Irish Stallion Farms EBF Maiden at the south Dublin course.
The winner was ridden by Limerick jockey Chris Hayes and is owned, trained and bred by Luke Comer.
It is the biggest priced winner ever in both Ireland and the UK.
The longest priced winner in an Irish race previous to today was 200-1. That was Killahara Castle in a December 2017 novice hurdle in Thurles. In November 1990 Equinoctial won at Kelso, going off at 250/1.
It was just He Knows No Fear's second ever race. In its previous run, which was last month in Limerick, the horse finished 12th of 14 runners, going off at 250/1.
— Racing TV (@RacingTV) August 13, 2020