Racing Demon is set to have a new man in the plate when he reappears in the totesport.com Peterborough Chase at Huntingdon on Saturday.
Graham Lee was on board when the seven-year-old, from Henrietta Knight's West Lockinge stables, near Wantage, struck in the race 12 months ago, giving her an incredible seventh win in the Grade 2 feature.
But Lee is set to partner Aces Four in either the Peterborough or the Betfair Chase at Haydock, leaving Knight searching for a temporary replacement.
"I don't think Graham will be able to ride Racing Demon, because if he rides Aces Four at Haydock he won't be able to get in a helicopter and fly down to Huntingdon," she said.
"We had hoped he would, but I think the timing will be too tight, and Aces Four might run at Haydock or Huntingdon, so I think we might have to say goodbye to Graham on that day."
Knight added: "We'd have liked to have given him a run as he's usually at his best when he's been out. He's always a bit fresh first time.
"Having said that, he seems a much calmer horse this year."
Meanwhile, Knight is mulling over whether to send Aztec Warrior to Ascot or Haydock on Saturday.
The promising six-year-old has entries in the Amlin Chase over three miles, three furlongs at the Berkshire course and in the three-mile Betting As It Should Be Handicap Chase on Merseyside.
COSSACK Dancer, trained by Mark Bradstock at Letcombe Bassett, near Wantage, sprang a 22-1 surprise at Folkestone on Tuesday.
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