Joe Fanning will see a specialist on Friday to ascertain the full extent of an arm injury suffered in a fall at Musselburgh on Wednesday.
Winner of the Gold Cup at Royal Ascot last year with Subjectivist, Fanning was riding the Jim Goldie-trained Braes Of Doune at the Scottish venue when his mount ducked left and unshipped him after a furlong.
Fanning, 51, walked gingerly away from the fall, but was taken off his booked rides at Haydock on Thursday and looks set to sit out the weekend action, too.
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Fanning's agent, Niall Hannity, said: "He's going to see a specialist in York, so we'll know more then.
"There's a lot of swelling at the top of the arm, so we'll see, but he won't ride a few days, which is the best-case scenario.
"I think we'll have to wait for the swelling to go down to get a fair gauge of what's what."