Trainer Aidan O’Brien will enter multiple Group 1 winners Henrythenavigator and Duke of Marmalade in the $5-million Breeders’ Cup Classic (G1) on October 25 at Santa Anita Park.

O’Brien already has retained jockey John Velazquez to ride whichever colt Ballydoyle stable jockey Johnny Murtagh does not pilot in the 1 1/4-mile race, which will be run for the first time on a synthetic surface.

Duke of Marmalade and Henrythenavigator will make their first starts on a synthetic surface, in this case Santa Anita’s newly installed Pro-Ride surface. The Classic also will be Henrythenavigator’s first race longer than one mile.

"Both horses have had long seasons," O'Brien told the Independent. "But we feel they're still in good form. Obviously, we think they'll be OK on the surface, though you never know until you try it in race conditions.”

The Classic also will include North American Horse of the Year Curlin, who won last year’s Breeders’ Cup Classic Powered by Dodge on a sloppy main track at Monmouth Park.

Other possible starters for the Classic include Casino Drive, Colonel John, Go Between, Smooth Air, Student Council, Tiago, and Well Armed. Dual classic winner Big Brown was pulled from consideration for the Classic on Monday after injuring his hoof during a turf workout at Aqueduct.