Dandyleekie got up right on the line to foil odds-on favourite Araner in the Requinto European Breeders Fund Maiden at Navan.
The market leader bowled along with the help of the rail and looked like he might have done enough but he was was strongly pressed by Ger Lyons' newcomer through the final furlong.
The pair flashed past the post almost as one, but 16-1 chance Dandyleekie was quickly called the winner by a head in the hands of Gary Carroll.
Lyons said: "His work was always good, but we weren't sure if we were going run him as he was very weak.
"We hoped it would be a nice experience bringing him to Navan and we can build for the season from this.
"We always thought he had ability and he will be on the team for Royal Ascot now.
"Gary says he's still very weak, but it's a nice option to have. There should be masses of improvement to come and it bodes well for what we have at home."