Bryan Cooper will miss today's meeting at Ascot after hurting his shoulder in a fall at the track yesterday.
The leading Irish rider was partnering the Colin Tizzard-trained 5-4 favourite Sizing Tennessee in the Tindle Newspapers Beginners' Chase in the colours of the late Alan and Ann Potts when he was unseated at the second fence.
Cooper gave up his one remaining ride and went for precautionary X-rays, which Dr Adrian McGoldrick, senior medical officer for the Irish Turf Club, reports to have come back clear.
However, Cooper will be now be sidelined for a couple of days before seeking further medical advice next week.
McGoldrick said: "He has been stood down until he sees Dr (Paddy) Kenny (consultant orthopaedic surgeon) on Tuesday. The initial X-rays came back clear, but he will likely have a CT scan to make sure.
"He's sore, hopefully it is just bruising, but we will know more once he's seen Dr Kenny."
Robert Dunne now takes over from Cooper aboard the Tizzard-trained Sizing Granite in the Christy 1965 Chase at Ascot.