Donnacha O’Brien upstages dad Aidan by landing the Nassau Stakes with Fancy Blue at Goodwood

The O’Briens dominated day three of Glorious Goodwood but it was 22-year-old Donnacha who stole the show by landing the Group One Nassau Stakes with Fancy Blue, his first runner in Britain.

Half an hour earlier, his father Aidan had landed the Group Two Gordon Stakes with Mogul but neither the most dominant Flat trainer in Europe nor his eldest son Joseph had the instant impact of his youngest son, who retired as a jockey last year after landing his second Irish champion jockey title as his weight rose.

Donnacha only had his first runners in February. He has had seven winners from less than 50 runners in Ireland, finished second in the Irish 1,000 Guineas with Fancy Blue and won the French Oaks with her.

Fancy Blue fended off fellow Irish raider One Voice to win the Nassau Stakes at Goodwood

His regard for Ryan Moore-ridden Fancy Blue could persuade Donnacha to aim his filly at the Prix de L’Arc de Triomphe at Longchamp in October via a race at next month’s Irish Champion weekend.

That could set up a clash in Paris not only with Enable but his father’s English 1,000 Guineas and Oaks winner Love.

Fancy Blue, who pulled out more when runner-up One Voice threw down a big challenge, has been looked after by Donnacha since she was a yearling but she ran under his father’s name last season when winning a Listed race at the Curragh.

The young trainer said: ‘You never expect this in your first year. It’s unbelievable I get a filly like Fancy Blue. People go a lifetime without getting anything like her. With a fillies’ allowance in the Arc, I would not be writing her off.’

Moore-ridden Mogul, who beat Highland Chief three-quarters of a length in the Gordon Stakes, also has a French appointment and a potential clash with Derby winning stablemate Serpentine in the Grand Prix de Paris on September 13.

Throughout the winter Mogul was reputed to be Aidan O’Brien’s main Derby hope but his trainer said he had needed his first two runs — when fourth at Royal Ascot and sixth in the Derby — too much.

Santiago, the Goodwood Cup third, remains the main St Leger hope of O’Brien Snr. That race is also the likely destination of Gordon Stakes third Subjectivist and fourth English King.

Supremacy looked ready for a try at Group One level after giving trainer Clive Cox and jockey Adam Kirby their second successive win in the Richmond Stakes.