Empress Josephine edged out stablemate Joan Of Arc with a late burst to win the Irish 1,000 Guineas in a photo finish at The Curragh.
The 14-1 shot and jockey Seamie Heffernan came strong at the finish to make it a one-two for Irish trainer Aidan O'Brien.
No Speak Alexander (13-2) had led from the front and looked to be locked in a duel with 9-2 second favourite Joan of Arc, but came home third.
Belle Image was fourth.
Empress Josephine beat her stablemate on the bob by a short head, making it a fifth victory in the race for Heffernan as 15-8 favourite Pretty Gorgeous's challenge faded.
It was a 10th Irish 1,000 Guineas win for trainer O'Brien.
"I thought I had got there. I had a winning partner and should have won well but I was a lucky winner," Heffernan told RTE.
"Irish racing is always tactical. If you don't have a horse that can jump and travel in the first four you are on the back foot. Irish racing is getting more like French racing, and it's been like that for a while.
"I'm delighted to be on this one, she is very well bred. She did a good job. I'm as hungry as ever."
Elsewhere, Irish jockey Rachael Blackmore finished out of the places on Ajas in the Grand Steeplechase de Paris, which was won by Docteur De Ballon for the second year running.
The victor, ridden by Bertrand Lestrade, is trained in France by England-born trainer Louisa Carberry.
She is married to Philip - the Champion Hurdle-winning jockey, who is part of the Carberry Irish racing dynasty.
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