Richard Dunwoody was looking forward to a return to race-riding on Friday after treatment yesterday.
The former British champion jump jockey aggravated an old neck injury - which forced him onto the sidelines for 10 weeks last summer - when riding Princeful at Doncaster on Monday, his 35th birthday.
But his acting agent Graham Dench, standing in for the holidaying Robert Parsons, said: "He's had physio today and they have told him not to ride until Thursday. So he plans to ride out on Thursday and, all being well, return to race-riding at Ascot on Friday."
Harding Back
Meanwhile, Brian Harding makes a quick return to action today after giving up two rides at Doncaster on Monday. He has made a speedy recovery from the effects of a fall on Imperial Fountain which left him dazed.
"He is fine and has been schooling at Micky Hammond's this morning," said the Corkman's wife Sarah said yesterday.
"He was just a little bit groggy but he has no problems now and he will be back in action at Huntingdon tomorrow."
A South African jockey has been killed after being thrown from his mount in a race at Gosforth Park last weekend.
Craig Magua, 35, sustained severe head injuries after his mount, Whistling Nun, fell and somersaulted over the rider 50 yards from the line.
Magua never regained consciousness. He is the first rider to die from racing-related injuries on a South African racecourse in over 40 years.
Jenny Pitman was yesterday no more than "hopeful" that her 2000 Cheltenham Gold Cup hope Princeful will be able to race again.
X-rays show that her high-class staying hurdler fractured a pedal bone in his left hind leg when coming to grief on his first run over fences on Monday.
The trainer, who initially thought the gelding had just sprained a joint, said Princeful had "a comfortable night" but in a statement yesterday she added: "The prognosis for a return to racing, whilst we are hopeful, must be guarded."
The eight-year-old suffered his injury on his chasing debut in a novice event at Doncaster in which he came to grief at the seventh-last fence.
A fractured pedal bone is a potentially career-ending injury and caused the retirement of three-time Gold Cup winner Arkle in 1968.
