Donnacha O'Brien's Fancy Blue beat compatriot One Voice in a thrilling finish to the Group One Qatar Nassau Stakes at Goodwood on Thursday.
The Prix de Diane winner was sent off at 11-4 after a late plunge for owner-mate Magic Wand (9-4), trained by the winning trainer's father, Aidan, but the money was misplaced as the daughter of Deep Impact prevailed.
Ryan Moore has won the race on Minding and Winter in recent years and he was the winning jockey once again, steering Fancy Blue into the lead in the final furlong as pacesetter Magic Wand wilted.
Instead the big challenge was laid down by Value Bet selection One Voice (20-1) with Jessica Harrington's filly emerging from the pack under Tom Marquand.
It looked like she might get there thanks to a strong late run, but to the winner's credit Fancy Blue pulled out more when challenged for a neck success.
Nazeef looked like she might drop out to be last approaching the final furlong, but she stayed on powerfully once organised to claim third.
"This filly's done nothing wrong," Moore said afterwards.
"She ran well in the Irish Guineas, she won a Diane - they're hard to win - and now she's come here and beaten the older fillies.
"She was happy enough today on this ground, I'd just say she wouldn't want extremes."
Making it even more special for the 22-year-old O'Brien was the fact Fancy Blue was a first runner in Britain for his stable.
He said: "We were very happy with her coming into the race. Her work had been really good, she was in fantastic form and everything had gone perfectly to plan, so we were full of confidence.
"We'll give her a little break now as she's had a busy start to the year and there's not much for her for a few weeks.
"We might look at Irish Champions Weekend, whether that's going back to a mile for the Matron Stakes or running in the Irish Champion Stakes, we'll see.
"After that we'll probably go on to Arc weekend, where she could run in either the Prix de l'Opera or the Arc itself.
"After that it will either be the Breeders' Cup or there is a race for her in Japan in the middle of November - the Queen Elizabeth, I think it is. It's a race for big money and she gets a bonus for that after winning the Prix de Diane.
"I'm sure the Japanese people would love to see her (as a daughter of Deep Impact). I know from when I was riding Saxon Warrior (a son of Deep Impact) he got a good following from the Japanese fans and it was somewhere I always wanted to go.
"We're not really sure what's going on in America and what will happen to the Breeders' Cup, but they're the options we're looking at."