Aidan O'Brien had to settle for second place in the feature event, the Pretty Polly, but Sunday's meeting at The Curragh was still cause for a family celebration.
O'Brien's daughter Sarah rode her first winner when Beach Of Falesa, owned by her mother Anne-Marie, won the Ladies Derby.
Her proud father and the horse's trainer said it was a special thrill.
"That's great, I'm delighted - that's a special one," O'Brien said.
"We appreciate everybody has done a lot of hard work with the filly and we appreciate Mr and Mrs Magnier, who own half of her, letting Sarah her.
"It was a great chance for her to come here, so it's a massive day - and a great track to do it on. It's a special weekend, unbelievable."
The young jockey, whose elder brother Joseph is a multiple Group One winning rider, said she hoped to keep the momentum going.
"It's brilliant - race-riding - I love it," she said.
"The filly doesn't like to get to the front too early so the way the race went suited me well.
"I'll keep riding away. Hopefully I'll go to college next year and keep riding plenty. I used to ride a lot of ponies but I'm concentrating more on racehorses now."
The Aidan O'Brien-trained Was failed by a half length to catch Ambivalent in the Pretty Polly with the winner giving English trainer Roger Varian a first Irish Group One victory.