John Oxx's highly-regarded Akeed Mofeed went down narrowly to the Aidan O'Brien-trained David Livingston in the Juddmonte Beresford Stakes at the Curragh.
The 5-6 favourite gamely tried to wear down his more experienced rival, but could not quite make up the deficit in the very testing conditions.
Seamie Heffernan had National Stakes third David Livingston (7-2) in front from the start, while Akeed Mofeed was untidy coming out of the stalls.
He soon recovered the lost few lengths to sit third, but floundered as he got into a barging match when asked for his effort.
Once on an even keel, Akeed Mofeed made up ground hand over fist for Johnny Murtagh but could not quite get to the leader and was still half a length down at the line, in a race won three years ago by Sea The Stars.
O'Brien said of the winner: "He's a hardy horse. It was a good performance on soft ground to lead all the way and he quickened up well.
"He was entitled to get a little bit tired. We're delighted with him - it was tough going out there.
"We'll look at the Racing Post Trophy and the French races, but he's raced plenty this year and it's not important if he doesn't run any more.
"I'd say he'll stay next year and he might be a horse that starts off in the trials. He'll love a mile and a quarter."
Akeed Mofeed is unlikely to run again this season, but could also be seen in a trial next spring.
Bruce Raymond, racing manager to owner Jaber Abdullah, said: "The ground was a bit too heavy for him and he just couldn't get a blow in at the leader.
"The leader looked as though he got away from him two out and he just couldn't make up the ground in those conditions. He was making it up steadily, but he ran a good race.
"It was very heavy ground and he just didn't have the experience to handle it.
"He's a potentially good horse and he won't run again this year.
"Hopefully he might be aimed at one of the trials. I'd be surprised if it was one of the Guineas trials, it's more likely to be a Derby trial, but it's a long way away."
O'Brien had earlier struck with Nephrite (6-1), who looked a smart prospect in foiling a gamble on Bird's Eye View in the Irish Stallion Farms EBF Maiden.
There was a massive plunge on the Tommy Stack-trained Bird's Eye View, with JP McManus's filly backed down from 20-1 to 11-2 favourite.
However, she did not get a clear run through and had to settle for third place as Joseph O'Brien enjoyed a dream passage on fellow newcomer Nephrite (6-1) on the stands rail to win by four lengths from Big Blue Spirit.
"He was just ready to start and was working nicely at home. He could be a horse for something like the Group Three Killavullan Stakes at Leopardstown at the end of October," said O'Brien.
The Ballydoyle maestro made it a treble when Harrison's Cave (5-1), also ridden by his son, took the Free Admission Curragh Races 9th October Maiden.
Patrick Prendgergast believes Coral Wave could be an Irish Oaks candidate next year after she put up a gritty performance to take the C. L. Weld Park Stakes.
Declan McDonogh asked the 4-1 shot to go on two furlongs out and she battled bravely in the stamina-sapping ground to hold on by a neck from Homecoming Queen.
Prendergast, celebrating his first Group winner, said: "She loves that ground. She's changed a lot as she was a little bit free in the spring on her second run.
"She's still a little bit on the weak side and will go home to Grangecon Stud now for the winter.
"Next year over a mile and a half she might not need it soft as her stamina will come into play more.
"I'm thinking of the Irish Oaks for her."
David Nagle's Maarek (15-2) ploughed through the ground to land the spoils in the Irish Stallion Farms Joe McGrath EBF Handicap by a length from Kevin Ryan's Murura, the 7-1 favourite.
Rock And Roll Kid (9-4 favourite), trained by Tony Mullins and ridden by his son, Danny, just denied Bay Knight by a short head in the Irish Pony Club Raceday Trophy.
Trainer Dessie Hughes is more renowned for his jumpers but he enjoyed a victory at Ireland's Flat HQ with 11-2 favourite Sun Disc in the Derek O'Sullivan Memorial Apprentice Handicap.
