Ahead of the biggest week of the Flat racing calendar, jockeys' championship leader Oisin Murphy was forced to miss five rides at Salisbury after failing a breath test for alcohol on Sunday.
Murphy, 23, is set for a host of big rides during Royal Ascot, which starts on Tuesday, but was unable to add to his tally of 96 wins for the year after Salisbury stewards stood him down for the day.
On the mark with a double at Sandown on Saturday, including New King for his boss Sheikh Fahad Al Thani, who celebrated his 30th birthday on the same day, Murphy has ridden 47 winners in the Stobart-backed title race and is the general 2-5 favourite to join the likes of Lester Piggott, Pat Eddery, Frankie Dettori and Ryan Moore as a champion rider.
Steward Richard Westropp said: "Oisin was tested, as were all the jockeys riding here today. However he tested above the permitted level for alcohol and was therefore unable to take his book of rides. The matter has been forwarded to the BHA."
The alcohol limit for jockeys is set at 17 micrograms per 100ml of breath, whereas the UK driving limit is 35 micrograms per 100ml.
A former champion apprentice, Murphy enjoyed a stellar 2018 with nine Group 1 triumphs, including the Coral-Eclipse, Juddmonte International, Qipco Irish Champions Stakes and Qipco Queen Elizabeth II Stakes on Champions Day on Roaring Lion for Qatar Racing and John Gosden.
He was also successful on Signora Cabello, who he rides in the Group 1 King’s Stand Stakes, in the Queen Mary Stakes at Royal Ascot last year.
Murphy spent Sunday morning on Racing TV's Luck On Sunday programme, when he demonstrated why he is regarded as one of the sport's most eloquent and compelling participants.
He is booked for five rides at Windsor on Monday night and six on the opening day of Royal Ascot on Tuesday.
Qatar Racing's adviser David Redvers did not comment on the situation, while the Racing Post attempted to contact Murphy without success.