Wexford rider Bertram Allen took first place and €50,000 in prize money at the five-star Lummen Grand Prix in Belgium.
In a starting field that saw 50 of the world's best riders compete for a share of the prize pot on offer, the 18-year-old was flawlessly consistent through all three rounds and recorded one of only two triple clear scores achieved in the competition.
Allen and Ballywalter Farms's ten-year-old grey mare Molly Malone V finished a third of a second faster than their nearest challenger, Dutch Olympic team medallist Jur Vrieling and the nine year-old gelding Flash Dance vd Kalevallei.
Irish show jumping manager Robert Splaine said: "To win a five-star Grand Prix at just 18 is a tremendous achievement for Bertram, and the future is certainly bright for him. Bertram also contributed as a team member towards Ireland's joint third place in the Lummen Nations' Cup on Friday, and it's worth noting that all four members of that team have now had individual wins at Lummen. Bertram has polished off what has been a fantastic week for Irish show jumping here."