Brendan Powell will not be able to return to the saddle tomorrow but has not ruled out being able to ride Young Kenny at Uttoxeter on Saturday.
The jockey has been absent since injuring his ribs in a fall at Doncaster on Friday, having only recently returned from a two-month lay-off.
Powell had hoped to return at Towcester tomorrow but a problem emerged when he was riding out this morning.
Powell said: "I've got a trapped nerve in my shoulder which I've been having trouble with for the last few days.
"I thought I'd got rid of it after the last accident but unfortunately when I fell the other day I landed smack on the point of the shoulder again and aggravated it.
"I was getting on a horse this morning and it caught me again. The ribs and everything are fine.
"I'd be hopeful of getting back for Saturday but I'll just have to see what the physio says this afternoon."
