IRIDESSA HELD OFF Vasilika by a neck to win the $2 million Filly & Mare Turf at Santa Anita on Saturday to make Ireland’s Joseph O’Brien the youngest trainer ever to saddle a Breeders’ Cup winner.

Longshot Mirth raced to an early lead with Vasiliska in second and Iridessa — who went off at 13-1 from the inside post under jockey Wayne Lordan — tucked in behind.

Iridessa and Vasilika surged to the front at the turn, Iridessa seizing the lead and repelling a determined fightback from Vasilika at the wire.

The Chad Brown-trained Sistercharlie, trying to repeat her victory in the same race at Churchill Downs last year, went off the 4-5 odds-on favorite but finished third.

“That was fantastic,” said O’Brien. “Wayne gave her a great ride and got into a really nice position early on.

“This is unbelievable,” added O’Brien, the son of famed Irish trainer Aidan O’Brien who was already the youngest jockey to win a Breeders’ Cup race thanks to his victory aboard St. Nicolas Abbey in the 2011 Turf.

At 26, he takes over as the youngest trainer to win from Craig Dollase, who was 27 when he saddled 1998 Sprint winner Reraise.

Joseph O’Brien joined France’s Freddy Head as the only person to both ride and train a Breeders’ Cup winner.

Head won the Mile twice aboard Miesque and trained Goldikova to three Mile triumphs.

“Unbelievable feeling,” Lordan said. “She was so tough to dig deep and hold on. It was some performance.”