Former champion jockey Jamie Spencer has lost his appeal against a two-day riding ban and is likely to miss the Epsom Derby meeting in June.
Spencer was champion Flat jockey in the 2005 season
He appealed to the Horseracing Regulatory Authority over the penalty imposed at Ascot on Saturday.
It ruled him of action on 23 and 24 May, but the Irish rider then picked up a separate 10-day riding ban in France.
Unless his appeal against the French suspension is successful, he will miss the Epsom fixture on 1 and 2 June.
The 26-year-old rider was found guilty of not riding out for sixth place aboard High Heel Sneakers at Ascot on Saturday.
Having heard evidence from the jockey and viewed video recordings of the race, the HRA's disciplinary panel upheld the decision of the Berkshire stewards.
On Sunday, Spencer was handed a 10-day suspension at Longchamp for careless riding aboard fourth-placed Excellent Art in the French 2000 Guineas.
That ban was due to run from 22-31 May inclusive and the HRA informed the French authorities that the two suspensions coincided.
In that case, new dates will be put forward for the 10-day ban should Spencer's appeal to France Galop fail.
It is thought Spencer's second suspension would begin the day after his Ascot ban ends and run until 4 June, ruling him out of both Epsom Classics - the Oaks and the Derby.
He has ridden four times in the Derby, with his best finish of third coming on Moon Ballad in 2002.