The Ballydoyle maestro has been in exceptional form this season and will be looking to secure a third successive victory in the Classic after Alexandrova and Peeping Fawn bagged the last two renewals.
O’Brien is responsible for seven of the 18 fillies engaged and is looking forward to unleashing a strong team headed by Moonstone, runner-up in the Oaks at Epsom last month.
“Moonstone will run, as will Ice Queen. Gentle On My Mind is also a confirmed runner, as is Adored,” said O’Brien.
“I may also run another one but they are my four main contenders.
“Moonstone is in great form and has come on a good bit since Epsom.
“We’re hoping for a big run from her.”
Moonstone beat all bar Ralph Beckett’s Look Here at Epsom and is the 6-4 favourite with Cashmans to go one place better in the Irish equivalent.
Darley Irish Oaks
Cashmans bet: 6-4 Moonstone, 3-1 Katiyra, 5-1 Gagnoa, 11-2 Mad About You, 6-1 Chinese White, 16-1 Adored, Gentle On My Mind, 20-1 Rosa Grace, Icon Project, 33-1 Prima Luce, 50-1 Ice Queen, 66-1 Honoria, Love To Dance, 100-1 Festival Princess, Perihelion, Silk Affair, 500-1 Summercove.
Meanwhile O’Brien’s Plan, who currently sits a long way down in the weights for the 49th John Smith’s Cup at York, will instead run at the Curragh on Saturday.
The Storm Cat colt finished fourth in a Listed event at the track last month but will climb a rung higher to tackle the Group Three Keeneland International Stakes.
Plan will form part of a strong O’Brien team being readied for action this weekend.
Outlining some of his other intended runners, he said: “We will run Georgebernardshaw in the Minstrel Stakes and have decided to run Plan in the Keeneland International.
“The plan was to go to England but we’ve decided to stay at home with him.
“We’ve seven horses in the race but we’ve decided to run only Plan.
“In the Rockingham I will be running Abraham Lincoln and Great Rumpuscat and in the Anglesey I’m running Egypt, Grand Ducal and Westphalia.”