Martin Ferris faces three months on the sidelines after breaking his left leg in a fall at Galway on Monday.
The jump jockey sustained the injury in a spill from Golden Rebel at the ninth fence in the Ennis Lifts Handicap Chase.
He was taken to Galway University Hospital where he was due to undergo surgery.
"Martin's got a fracture of his left tibia and fibula. He's having surgery today," said the Turf Club's senior medical officer, Dr Adrian McGoldrick.
"He'll be out for three months."