Nathaniel's full-sister Great Heavens bids to put her own name up in lights in the Darley Irish Oaks at the Curragh on Sunday.

Winner of all three starts this season, and beaten just once in her career, like Nathaniel she is trained by John Gosden and owned by Lady Rothschild.

Great Heavens was last seen sluicing up in testing ground at Haydock in the Lancashire Oaks, on the same afternoon Nathaniel won the Coral-Eclipse.

Connections took the decision earlier this week to supplement her for the Curragh heat, although in-form Newmarket trainer Gosden is slightly wary of the proximity of that Haydock run.

"Obviously it is very tight between races after such a huge effort in the Lancashire Oaks, where the time was a second and a half quicker than the Old Newton Cup," said Gosden.

"She seems fine. She has shown she can handle really soft ground."

By contrast to the Great Heavens camp, connections of Princess Highway are concerned about underfoot conditions.

Dermot Weld's filly could not have been more impressive in the Ribblesdale Stakes at Royal Ascot and had been the general ante-post favourite for this weekend's fillies' Classic.

However, news of a minor problem came to light earlier this week and with further doubts about the ground, she has been usurped at the head of the market by the Gosden runner.

Weld said: "She's very well but we had a little hold-up earlier in the week.

"She's over that, but she will find that testing ground against her."

Princess Highway's jockey Pat Smullen voiced similar concerns about the prospect of bottomless ground.

"She's done everything right leading up to the race. She was very impressive in Ascot," he told At The Races.

"She appears to be in the same sort of form she was then. The big concern for me is the ground.

"In the formbook it says it was soft at Ascot, but it was nothing compared to what she will encounter on Sunday.

"She is going to encounter heavy winter ground here on Sunday and that is an unknown to her.

"She is very well, but I just hope she handles conditions."

The third major challenger for top honours is Aidan O'Brien's Epsom Oaks heroine Was.

Princess Highway beat that rival in the Blue Wind Stakes at Naas in May and Smullen is hoping his mount can confirm the form.

He said: "Granted Was had probably improved since Naas, but her (Princess Highway) form is the strongest at the moment, in my opinion."

Was was due to run in the Pretty Polly Stakes after her Epsom heroics, but was withdrawn because of the testing ground.

Conditions are once again a concern.

Jockey Joseph O'Brien said: "The ground might not be ideal, but it's the Oaks so we'll take our chance and see what happens.

"She's still a lightly-raced filly and hopefully she'll run a good race."

Hughie Morrison's Shirocco Star was narrowly beaten by Was at Epsom and was third behind Princess Highway at Ascot.

The East Ilsley handler said: "She seems fine and it's quite rightly a very competitive race.

"We've been beaten by a couple of them before, so we know it's going to be difficult, but she's been second in one Oaks and we wanted to have a go at another.

"We don't know how she'll handle conditions. She might hate it and if she does, we'll have learned our lesson."

O'Brien also runs Twirl and Devotion, with the Eddie Lynam-trained Colliding Worlds, who was also supplemented, completing the seven-runner field.