Frankie Dettori was left red faced after celebrating victory aboard Lady Aurelia in Friday's Group I Nunthorpe Stakes (5f) at York.
Dettori celebrated after crossing the line believing he had held on however, the photo finish showed otherwise with Marsha winning by the narrowest of margins, the pair 3 3/4-lengths clear of Cotai Glory (50/1) in third.
The Wesley Ward-trained Lady Aurelia had been matched as low as 1.12 on betting exchanges in the run, starting the 10/11 favourite with Marsha at 8/1.
Dettori admitted he had got it wrong when questioned by the media on Racing UK.
"Ow! - You saw it yourself. I thought I had won a neck. You've seen it on TV. I'm shocked lads." Dettori said.
Another incredible #ClassicEbor finish as Marsha pips favourite Lady Aurelia in the Coolmore Nunthorpe Stakes ▶️️ https://t.co/7iJOPsvjqxpic.twitter.com/CocWdX1al2
— Racing UK (@Racing_UK) August 25, 2017
There was no talk of The Everest at Randwick in October for Lady Aurelia, who is likely to return to North America for the Breeders' Cup Turf Sprint at Del Mar on November 2.