English and Irish Derby winner Auguste Rodin won the Irish Champion Stakes at Leopardstown with another Aidan O'Brien-trained runner Luxembourg finishing runner-up.
Jockey Ryan Moore held off a late challenge from Luxembourg to win on the 11-4 favourite, with Nashwa third.
Meanwhile, at the Sprint Cup at Haydock, Regional denied Shaquille a seventh straight win.
It is a first Group One win for trainer Ed Bethell and jockey Callum Rodriguez.
Shaquille looked strong early on before falling away in the final two furlongs to finish last, leaving Regional to charge home by a neck despite a strong challenge from 50-1 outsider Shouldvebeenaring, who took second.
Auguste Rodin had flopped in the King George at Ascot last time out but bounced back to give O'Brien his 12th win in the race and fifth in succession.
"He's a very brilliant horse, very tough and very hardy, but he's a little bit peculiar," he said.
The winner could now be aimed at the Breeders' Cup Turf in the United States later in the year.