Donnacha O’Brien is confident there will be plenty for his family to cheer at Del Mar when Porta Fortuna bids to break his own Breeders’ Cup duck and City Of Troy attempts to give his father Aidan a historic first success in the Classic.

The 26-year-old never found the scoresheet at the Stateside showpiece as a jockey, but came close to glory as a trainer at Santa Anita 12 months ago when Porta Fortuna rattled the crossbar in the Juvenile Fillies Turf.

She has since dominated against her own sex over a mile in Britain and Ireland and after winning her third Group 1 of the campaign in the Matron Stakes last month, the daughter of Caravaggio is poised to board the plane once more for another trans-Atlantic mission.

Porta Fortuna will be competing against colts and geldings for the first time in the Breeders’ Cup Mile, but her handler is confident she has all the attributes to thrive in an all-star field that could include Charlie Appleby’s 2000 Guineas hero Notable Speech and Christopher Head’s Ramatuelle.

“All is on course and she has a few more bits of work to go, but all is going well so far and we’re on track,” said O’Brien.

“It’s going to be a very good race and there is no doubt about it, it is probably going to be the strongest field she has ever faced. She’s a filly who is progressing with every run and she’s enjoyed a super season, so I think she has deserved a crack against the boys and we will see what she can do.

“She ran a cracker at the Breeders’ Cup last year, she’s the kind of filly that’s very tactically versatile in terms of European racing, but it is also a big advantage when you go to America.

“It means you can break on terms and get a decent position if you get a good draw, which is obviously going to be very important. I’m looking forward to getting her back over there.”

Porta Fortuna has been ridden in all but one of her four starts this term by Tom Marquand, who looks set to retain the ride in California.

Ryan Moore was in the plate when the three-year-old tasted Falmouth Stakes glory, but Marquand rode at Royal Ascot in the Coronation Stakes and at Leopardstown, leaving him with another live contender in America alongside last year’s Juvenile Turf Sprint champion Big Evs.

“I think Tom Marquand will ride her,” continued O’Brien. “He’s going to be over there for Big Evs and a couple of other horses and he obviously rode a Breeders’ Cup winner last year. He knows her very well and I’m not sure if it’s 100 per cent confirmed, but it’s looking like it will be Tom.”

Not only will O’Brien be saddling Porta Fortuna in the San Diego suburbs, he will be firmly in City Of Troy’s corner as his father’s latest Classic contender tries to end his all-conquering career in style.

Despite going close with the likes of Giant’s Causeway and Henrythenavigator in the 10-furlong event, the dirt showpiece has so far eluded the master of Ballydoyle.

However, his son believes City Of Troy represents his father’s best chance of Classic success in some time and is backing the son of Justify to showcase his supreme ability in America.

“I think it’s very hard to predict what a horse will do on dirt, but in my opinion it is the biggest chance he has had in a long time,” added O’Brien.

“He’s a horse that looks like he has the right attributes – he has early pace and is able to sustain a strong gallop, which you have to be able to do in America.

“I think draw and pace and just how the race works out for him will be very important, but I think if he could just get comfortable in the first few furlongs, I fancy him to go and win it.

“You will know after the first half-mile how it is going to go, but I think he is a best chance he will have had in a long time.”