Moore developed a sound association with the Galileo filly last season, but the star jockey was similarly taken by Cheshire Oaks winner Magic Wand.
O’Brien said: “I suppose Magical was a very highly-rated filly last year and she’s a full sister to Rhododendron, but I know Ryan was very happy with the filly he rode in Chester as well.
“It’s not going to be an easy one for him, but he’s probably going to find it hard to get off Magical. But that’s not to say that he won’t because I know he was very happy with the Chester filly and we were very happy with her also.”
O’Brien also plans to saddle Blue Wind Stakes winner Bye Bye Baby, while Cheshire Oaks runner-up Forever Together and I Can Fly are other likely Oaks contenders.
But speaking at the Breakfast with the Stars event at Epsom yesterday morning, the Ballydoyle handler said Happily, who finished third in the 1000 Guineas at Newmarket, will not run at Epsom.
He said: “She’s going to the Irish Guineas and there’s not a lot of time to come back.
Sea Of Class burst into the Oaks picture when successful at Newbury on Saturday, but she is not a definite runner at this stage. Trainer William Haggas said: “She won very well last week and it didn’t surprise us. My feeling is the Oaks will come too quick. I emailed Mrs (Ling) Tsui (of owners Sunderland Holding Ltd) the day after Newbury and I got a response this morning, but I need to speak to her in person.
“She’s quite keen to go, naturally. As she says, ‘There’s only one Investec Oaks’, but ultimately I think she’ll leave it to me. I’ve just got to discuss it with her. I’ve got her in the Ribblesdale and I’ve put her in the French Oaks. The French Oaks looks the right fit as it gives her a month from Newbury and it gives us time to go for the Irish Oaks as well.”
Haggas will, though, definitely be represented in the Classic with Musidora winner Give And Take.