Frankie Dettori has been left red-faced after a premature celebration on Lady Aurelia at the end of the Nunthorpe Stakes.

The photo-finish showed the American filly had been nosed out by the Sir Mark Prescott-trained Marsha in the Group One sprint at York.

"I'm in shock. I thought I'd won a neck," Dettori said.

Winning jockey Luke Morris admitted he thought he had just lost out.

"I wasn't sure and I saw Frankie put his arm up," Morris said.

"I was gutted as I thought he had won, then someone said congratulations to me and it turned into jubilation."

Prescott, who watched the race from Ireland, said the winner was likely to run in France rather than the Breeders' Cup at Santa Anita.

"They are two very good fillies and I'm very lucky the short head went my way," Prescott said.

"I think she's been tremendously consistent. She's been the best of the rest every time, really. To finish in front of Lady Aurelia on a flat track is a great performance.

"Lady Aurelia is a marvellous filly, so to be able to say we have arguably the fastest filly in the northern hemisphere, we are very lucky.

"She's owned by Elite (Racing Club) so she will probably have to be sold in the autumn, but if it did come up soft, it (Breeders' Cup) might be something to think about, but I think it will be the Abbaye next."

Wesley Ward was proud of Lady Aurelia and full of praise for the winner.

"She's a true champion, these things happen," he said.

"I think we got beat fair and square. It happens. I'm not going to make excuses.

"I thought we'd won simply because Frankie did, but that's racing. I have been second in this race twice now and it's tough to take.

"Hopefully I will be back another day and we will look towards the Breeders' Cup now."