Forever Together shed her maiden tag with a stunning victory in the Investec Oaks at Epsom.
Trained by Aidan O'Brien and ridden by his son, Donnacha, Forever Together was an 8-1 chance having failed to win any of her three previous starts, most recently chasing home stablemate Magic Wand in the Cheshire Oaks last month.
However, she reversed that form in some style, bagging the rail halfway up the home straight and readily pulling clear of 5-2 favourite Wild Illusion.
Bye Bye Baby was third.
Donnacha O'Brien told ITV Racing: "She was very impressive. I got a beautiful trip through, I followed Ryan (Moore, on Magic Wand) and he gave me a bit of company until I got to the rail.
"She's very genuine and galloped right out to the line, she's a proper staying filly."
He added: "I should have been closer at Chester, we just ran into a bit of trouble. About a week ago I thought she had a right good chance and then the rain came so I was a bit worried, but she's handled it really well.
"To be honest, I didn't expect her to do it. I had the perfect position the whole way. It all went perfect.
"When you're riding one of his (his father's) you have a chance, he's an absolutely genius.
Aidan O'Brien said: "It's incredible, I'm so delighted for everyone, so thankful to Michael (Tabor), John (Magnier) and Derrick (Smith), it's brilliant for everyone.
"She caught the eye at Chester, she's a staying filly and got the trip very well.
"She's obviously by Galileo and it's unbelievable. Donnacha gave her an unbelievable ride, it's incredible.
"We're all so happy and grateful."