Leading apprentice Michael Murphy is set for a spell on the sidelines after breaking his thumb in a fall at Nottingham on Sunday.
He was taken to Queen's Medical Centre as a precaution following his tumble from Martinas Delight, trained by his boss Alan Jarvis, but was allowed home last night.
The Irish-born 5lb claimer was unshipped when his mount clipped heels with the William Buick-ridden Close At Hand in the Sponsor A Race At Nottingham Racecourse Maiden Fillies' Stakes.
The stewards looked into the incident and as they were satisfied it was accidental, they took no further action.
"The William Buick-ridden horse moved over and Michael Murphy clipped heels," said Murphy's agent Simon Dodds.
"He's walking wounded but does have a broken thumb and is a little bit sore today.
"It means he will miss rides at Royal Ascot and it may possibly cost him the apprentice championship, but the important thing is he is walking wounded and we will get him back on the track as soon as he can.
"The next two or three weeks is the outline, subject to Dr Michael Turner (chief medical officer for the British Horseracing Authority)."
Murphy had five rides lined-up for Royal Ascot including Navajo Chief in the Royal Hunt Cup on Wednesday week.
The six-year-old gave him his biggest success to date in the Listed Hambleton Stakes (Handicap) at York last month.