Ruby Walsh will be sidelined for at least two months after breaking his arm in a fall in the opening race on the final day of the Cheltenham Festival.
The winner of three races at the festival, Walsh was diagnosed with a compound fracture of his right arm after parting company with Abbyssial in the Triumph Hurdle.
Walsh was leading the field over the second hurdle when he took a crunching spill, bringing down stablemate Adriana Des Mottes in the process.
He was taken to hospital where he underwent surgery.
Walsh's understudy at the Willie Mullins yard, Paul Townend, the rider of Adriana Des Mottes, rode in the second race but gave up after that as he was feeling too sore to carry on.
That left David Casey to step in for the ride on the stable's On His Own and take second place in the big race of the week, the Betfred Cheltenham Gold Cup.
Daryl Jacob also faces a lengthy spell on the sidelines after suffering multiple injuries in a dramatic incident before the Novices' Hurdle.
Jacob's mount, the Paul Nicholls-trained Port Melon, crashed into a rail before the race, throwing the rider to the ground in a spectator area and sending a Channel 4 camera position flying.
Jacob was taken to hospital where he was found to have broken his knee, leg and elbow.