Taghrooda has been the subject of considerable market support to complete a Classic double in Saturday's Darley Irish Oaks.
Owner Sheikh Hamdan Al Maktoum has the ultimate decision on whether the John Gosden-trained Taghrooda heads to the Curragh at the weekend along with Tarfasha, who was the runner-up at Epsom, are both declared on Thursday.
William Hill shortened the Sea The Stars filly to 4-7 favourite from 8-11, while Paddy Power offer the same price from 4-6.
"All the money has been for Taghrooda and nobody wants to back anything else," said William Hill spokesman Jon Ivan-Duke.
"We've seen lots of four-figure bets and she could be a dreadful loser for us.
"We opened up at odds of 8-11 but that has been snapped up and she will go off odds-on this Saturday. She has trounced the opposition before and she may end up being one of the best-backed Group One horses this year."
Paddy Power said: "The money we've seen for Taghrooda has been significant - she's the only one punters want to know."