Deep Impact filly Snowfall gave another blistering performance to became the 15th filly to complete the English/Irish Oaks double at the Curragh.
Aidan O'Brien's filly had blitzed her rivals at Epsom to win by a record margin of 16 lengths and she produced a similar display on home soil in the Juddmonte-sponsored Irish equivalent.
The early running was made by one of her three stablemates, La Joconde, in the eight-runner line-up, with Nicest and Willow close up.
Ryan Moore had Snowfall just off the pace until the field turned for home and it was not long before she made her move - and once she hit the front two furlongs out there was only going to be one outcome.
Snowfall was cut to 4-1 from 5-1 for the Prix de l'Arc de Triomphe with Coral and 4-1 from 11-2 with Paddy Power.
O'Brien said: "She's very smart and she has a lot of quality."
"We purposely let her down a little bit from Epsom because the season is going to roll on and it was soft ground at Epsom. The plan was to come here, go on to the Yorkshire Oaks and then she'd be ready for the autumn. I'm delighted with her and she's done very well from Epsom physically, she's got very big and strong.
"Ryan said she has a lot of speed. She goes very strong and she finishes out very well. We'll go one race at a time now, the Yorkshire Oaks first. We always thought fast ground was her thing and I was very worried in Epsom about her with that ground."
Image- Snowfall by Deep Impact