Tiger Roll's Grand-National winning jockey Davy Russell and Jack Kennedy will be sidelined through injury for several weeks.
The pair were injured at Limerick Racecourse on Sunday.
Russell, who won the Grand National at Aintree on the Gordon Elliott-trained Tiger Roll in 2018 and 2019, came off Doctor Duffy at the first fence in the Munster National.
Kennedy fell three flights from home when partnering Etincelle Lioterie in the opening Listed novice hurdle.
He had only recently returned to competitive action after recovering from a broken leg he suffered at the Dublin Racing Festival at Leopardstown in February.
The Irish Horseracing Regulatory Board’s senior medical officer Dr Jennifer Pugh said: “Davy Russell sustained a neck injury and has a fracture of his C6 vertebrae. Jack Kennedy fractured his left collarbone.
“Unfortunately they will both be out for a number of weeks.”
Tiger Roll's trainer Gordon Elliott has hinted the ten-year-old might make his seasonal reappearance on October 31.
The Ladbrokes Champion Chase at Down Royal is under consideration, where he could meet Paul Nicholls' Cyrname.
Tiger Roll was denied the chance to join Red Rum as a three-time winner of the Aintree marathon this year, after it was cancelled during the coronavirus pandemic.
