Jack Kennedy faces around six weeks on the sidelines after breaking his collarbone in a fall from Swordsman at Punchestown.
Kennedy sustained the injury when he was unshipped from the Gordon Elliott-trained gelding at the fourth fence in the Grade Three Buck House Novice Chase contest won by Jan Maat.
He was stood down for the day and further examination revealed the extent of the damage.
Dr Jennifer Pugh, senior medical officer for the Irish Horseracing Regulatory Board, posted on the IHRB Twitter feed: "Following a fall today punchestownrace, Jack Kennedy has a fractured collarbone which will rule him out for approximately 6 weeks."
Kennedy enjoyed another fine season last term, primarily for Elliott in the colours of Gigginstown House Stud, picking up six Grade One wins, three of them on top-class mare Apple’s Jade.