The son of Montjeu and Finsceal Beo, who was an eyecatching winner on his debut, also has the option of running in the Royal Lodge at Newmarket on Saturday.
Ol’ Man River is one of five remaining entries for the Ballydoyle handler in the Group Two which he has dominated down the years, with Geoffrey Chaucer giving him a 13th win last season.
Battle Of Marathon, Jacobean, Order Of St George and Smuggler’s Cove are also in the mix for O’Brien.
“All my horses for the weekend seem to be in good form,” he said.
“The ground would be crucial for Ol’ Man River as he needs it to stay good. We will wait and see what the weather does over the next few days and make a final decision on Friday morning.”
Ger Lyons has two smart types engaged in Bertie Le Belge and Convergence, while John Murphy hopes to run Seaforth, although the ground will also be key for him.
“We have a few nice ones that will make nice three-year-olds, but they won’t run unless there is some juice in the ground. We may run Seaforth but it will depend on the ground as he won’t run if it’s firm,” said Murphy.
Dermot Weld’s Tombelaine, the Ken Condon-trained Success Day and Clonard Street are other interesting contenders.
Kevin Ryan’s Salateen, impressive in a nursery at Doncaster, may step back up in class but he is the sole possible from overseas.
Ryan also has an entry in the C L & M F Weld Park Stakes in the shape of Calypso Beat, second on her last two starts in Group Three company but also a possible for the Rockfel at Newmarket on Friday.
Jim Bolger’s Lucida, who has two options at Newmarket this week, could also stay at home for the Group Three.
Kevin Prendergast’s Tamadhor, Jessica Harrington’s Lola Beaux and O’Brien’s Found are others to note.
The standout amongst the 13 entries for the Irish Field Loughbrown Stakes is Weld’s hugely exciting Forgotten Rules.
Racecourse manager Paul Hensey has tweeted that watering has already commenced.