Trainer Jessica Harrington claimed the biggest Flat racing win of her career as Alpha Centauri won the Irish 1,000 Guineas.
The 12-1 chance, ridden by Colm O'Donoghue, relished the good ground at the Curragh.
Aidan O'Brien-trained horses were second and third.
Could It Be Love (33-1), ridden by his son Donnacha, finished three-quarters of a length ahead of the 5-4 favourite Happily ridden by Ryan Moore.
Most of Harrington's highest-profile success has been in National Hunt racing, with Sizing John winning last year's Cheltenham Gold Cup.
Alpha Centauri was a runner-up in the Albany Stakes at Royal Ascot last year but she was well beaten on her seasonal return at Leopardstown in April
However, this time she reeled in long-time leader Could It Be Love to win by a length and three-quarters.
BBC racing correspondent Cornelius Lysaght
It's not unprecedented to scale the greatest heights in both flat and jump racing, as Jessie Harrington now has, but it's unquestionably rare.
So, by adding this to her great National Hunt successes in races like the Cheltenham Gold Cup and Irish Grand National, Harrington can be considered right up there among 'dual purpose' trainers.
Runners trained by Aidan O'Brien were second and third, while in Saturday's Irish 2,000 Guineas, won by 25-1 shot Romanised, O'Brien colts filled places two, three and four - whatever his reputation, even at home in Ireland, the world's top trainer is not entirely invincible.