A winner of six of her eight starts with her only defeats coming on debut and then at Royal Ascot in the Albany Stakes, she has carried all before her since, winning three Group Ones along the way.

Having dropped back from seven furlongs to win the Cheveley Park Stakes in brilliant fashion at Newmarket last month, she now heads the other way and back up in trip, tackling a mile for the first time and seeking a top-level win at her third different distance.

“Sun Goddess has a long stride and a great mind. She has great speed and is big and scopey,” said O’Brien.

“I didn’t think she would be early when we started her and she just loved her work. She’s by Sioux Nation and that’s a speed angle.

“Johannesburg won four Group Ones in different countries, including the Breeders’ Cup Juvenile (on dirt), but he wasn’t as scopey as this filly, who is on springs.

“She looks very special and looks like she could be (the best I’ve trained). She very special and very unique in everything she does.”

Sun Goddess will be stationed in stall nine in a race which will see her lock horns with Prix Marcel Boussac winner Green Empress – trained by O’Brien’s son, Joseph – for a fourth time this season.

“She’s able to go a very quick tempo and though she’s drawn out a bit she has a big, long, open stride which will help her,” continued O’Brien.

“She cost £120,000 which is a lot of money, but for what they can make she was not too expensive.”

Also in action on the opening night for O’Brien – who is locked with Bob Baffert on 21 Breeders’ Cup victories – is Great Barrier Reef and Haffner, who will go to post bidding to give O’Brien a fifth straight victory in the Brown Advisory Breeders’ Cup Juvenile Turf.

“Great Barrier Reef got the seven furlongs well in the Dewhurst after getting a bit of interference and it suggests he will get a mile, as he’s a very relaxed horse,” said the trainer, who saddled Gstaad to land this event at Del Mar a year ago.

“Haffner you would imagine would get the trip very well, I just hope it’s not too tight for him. We saw when he got a strong-run mile at Newmarket that he’s going to get a mile and a quarter next year.”

Also taking an early sight of Keeneland were some of O’Brien’s key players in Saturday’s Grade One contests, including Breeders’ Cup Turf pair of Irish Derby hero Benvenuto Cellini and Arc third Diamond Necklace.

Filly & Mare Turf hopeful Precise and Prix de la Foret scorer True Love were also put through their paces, with the latter attempting to follow up in the Breeders’ Cup Mile.