Amateur jockey JT McNamara has been airlifted to hospital after being seriously injured in a fall at the Cheltenham Festival.
The 37-year-old Irish rider was treated by paramedics after his mount Galaxy Rock fell at the first fence in the Fulke Walwyn Kim Muir Challenge Cup.
Racing was delayed for 30 minutes as the jockey was transferred from a course ambulance to an air ambulance.
McNamara was then flown to Frenchay Hospital in Bristol.
Also on Thursday, the David Pipe-trained racehorse Matuhi suffered a serious spinal injury and was put down after falling at the last fence in the Byrne Group Plate.
Earlier, jockey Davy Russell was taken to Cheltenham General Hospital with a punctured lung, which rules him out of riding leading contender Sir Des Champs in the Gold Cup on Friday.
The 34-year-old, who rode the horse to victory at last year's festival, was injured in a fall from Un Beau Matin at the last in Wednesday's Coral Cup.
He had the injury drained in hospital and took up his first two rides on Thursday, but the problems resurfaced and Russell returned to hospital.
McNamara was conscious after the fall but had difficulty in breathing and was placed into an induced coma, said Irish Turf Club chief medical officer Dr Adrian McGoldrick.
He said the jockey was placed on a spinal board as a precaution and would undergo scans in hospital.
Fellow jockey AP McCoy told BBC Radio 5 live: "It's a dangerous sport and it's a sight that you see that unfortunately crops up; we're very lucky we have excellent medical care. We just hope he's going to be OK."