Light Heavy was a tenacious winner of the Derrinstown Stud Derby Trial at Leopardstown for Jim Bolger and Kevin Manning.
Breeders' Cup winner Wrote was backed as though defeat was out of the question beforehand but having travelled strongly through the early stages, the 8-13 favourite was beaten soon after turning in.
It was let to his stablemate, the front-running Tower Rock (9-1), to lead the Ballydoyle charge but after a sustained duel it was the Light Heavy (15-8) who got on top close home.
Bolger said: "He managed to get there despite not liking the ground. He's not the same horse on that ground.
"He's a top horse with a will to win and lots of ability. He's not going to Epsom. I'm hoping for decent ground at the Curragh for the Irish Derby."
Bolger confirmed that Dewhurst winner Parish Hall will go for the Irish 2,000 Guineas, and could be in contention for the Investec Derby after that.
He said: "He definitely does not handle soft ground but he could go to Epsom after the Irish Guineas."