Red Marauder's eagerly-awaited comeback has been put back for a week after another minor setback.
Plans to run him in the Bagpipes Handicap Chase at Ayr had to be scrapped after the 10-year-old suffered an over-reach.
"It's nothing too much to worry about," said Mason's assistant Richard Guest.
"He was having a blow this morning when he just trod on his coronet band. It's not too bad but he's too good a horse to risk.
"It's a shame as I was confident he would have won the tomorrow. We're running Nosam in the same race now and I'm sure he'll have a good chance as well."
Red Marauder has been off the course with leg trouble since an impressive victory in the First National Bank Gold Cup Chase at Ascot in November 1998.
"He's been working very well and is certainly fit now," said Guest. "I'm sure that when he does run he'll prove that he's as good as ever."
Red Marauder is now likely to reappear in the John Smith's Handicap Chase at Wetherby tomorrow week.
