Mandatario made a winning start to his career when hanging on for victory in the Powerstown Stud European Breeders Fund Maiden at Gowran.
In doing so, the Jim Bolger-trained newcomer was following his top-class stablemate Trading Leather, who won this mile event 12 months ago.
Kevin Manning's colt was in the box seat two furlongs out but had to withstand a strong challenge from the twice-raced Kerkeni, who made up plenty of ground before failing by a short head as the line came just in time for the well-backed 13-2 winner.
Bolger was at Croke Park for the All-Ireland Football final, but his assistant Ger Flynn said: "Kevin said he's a big immature horse but he was smart away and did it well.
"It's very unusual to win here from such a bad draw (14) and he looks like a nice horse for the future.
"He was a bit babyish in the parade ring beforehand but we've always liked him, he was just a bit slow to come to hand."