Wayne Hutchinson will not return to competitive action until next week as he continues to recover from an injury suffered at Doncaster last month.
The leading jockey injured a foot when he fell from The Tourad Man on January 29 and was forced to watch on from the sidelines as his boss Alan King saddled five winners at Doncaster and Cheltenham the following day.
Hutchinson was initially expected to make a swift return to the saddle, but missed the whole of last week and will not be in action at the high-profile meeting at Newbury on Saturday.
His agent Chris Broad said: " I believe the plan is for Wayne to start riding out again on Monday with a view to coming back later that week.
"He has a bit of ligament damage to his left foot, which is still black and blue.
"It's muscular damage and it's just needing a bit more time than maybe we originally thought.
"It's frustrating and we could do without it, but it's just a case of giving it time.
"He's having physio treatment and hopefully he'll be back in action at some stage next week."