Aidan O'Brien's trio all finished as one in the Derrinstown Stud Derby Trial at Leopardstown, with Douglas Macarthur just holding off stablemates Yucatan and Capri
Emmet McNamara had the 7-1 winner at the head of affairs from the outset, but looked a sitting duck as Capri and then Yucatan launched their challenges.
Douglas Macarthur found plenty when asked, though, eventually prevailing by a diminishing margin of a head from Yucatan, with Capri a short head back in third.
O'Brien bagged a double when daughter Ana drove Belgravia (5-2 favourite) to victory in the Crew Of R116 Memorial And Irish Coastguard Maiden.< Bean Feasa broke her maiden tag in Group Three company, landing the Derrinstown Stud 1,000 Guineas Trial.
Jim Bolger's 10-3 favourite was beaten in a Gowran maiden a week ago, but surpassed that effort with ease, picking up the front-running Asking to win by two and three-quarter lengths under Kevin Manning.< Custom Cut produced a battling display from the front to land the Ard Glen Construction Amethyst Stakes.
Daniel Tudhope was happy to lead on David O'Meara's 9-2 chance and he just kept finding more, eventually repelling Raymonda by half a length.
Brother Bear made a winning debut for Jessie Harrington when taking the Irish Stallion Farms EBF Maiden.
Favourite Sioux Nation led entering the final furlong, but Colm O'Donoghue had all moves covered on the 9-1 chance and swept past before scoring by two lengths.< Pincheck made it a double for Harrington and O'Donoghue with victory in the Mortons Coaches Maiden.
The well-backed 3-1 chance looked short of room entering the final furlong, but got out of trouble in time and ran on well to beat Captain Hardship by a neck.
Shane Foley's well-judged ride got Damian English's Geological (20-1) home in the John Fitzpatrick Agricultural Contractor Handicap, while the Fitzpatrick Gallgher McEvoy Solicitors Handicap went to Sheila Lavery's Mandamus (7-1) under Leigh Roche.