Aidan O'Brien insists no-one can use the Pro-Ride surface as an excuse in the Breeders' Cup Classic.

The Master of Ballydoyle saw his pair of runners for the race, Duke Of Marmalade and Henrythenavigator, canter over a mile on Friday.

Afterwards he said of the surface: "I think it's as fair as it can get, really. With the surface, it's going to allow dirt horses and grass horses to compete in some kind of middle ground."

O'Brien is pleased with his pair ahead of Saturday's feature and is hopeful Duke Of Marmalade can bounce back from a rare below-par run in the Arc last time.

"The Duke has been an exceptional horse all year and you can see why," O'Brien told reporters at Santa Anita.

"He always steps up to the plate. He cantered well. We're very happy.

"It's great to be here and great to be taking part in such a great race. Duke is one of these horses who has danced every dance. You can see the physique of him and the power, the strength and the toughness. He has all the things. We look forward to seeing him running."