Trainer Paul Nicholls has confirmed that Ruby Walsh will now ride Kauto Stone in the William Hill King George VI Chase at Kempton on Boxing Day.
Walsh would have partnered Al Ferof, who has also been ruled out for the season, but will now replace the suspended Daryl Jacob aboard Nicholls' stablemate.
The Ditcheat handler has also earmarked several horses who could represent him in the Ladbrokes World Hurdle, a race the injured Big Buck's has won for the last four years.
"Ruby will now ride Kauto Stone in the King George and, looking at the World Hurdle, we have Wonderful Charm, Prospect Wells and perhaps even Tidal Bay to consider for that race," Nicholls told Betfair.
"Wonderful Charm has had a breathing operation since winning at Chepstow, and I may even consider Tidal Bay for the Cleeve Hurdle after he runs in the Lexus."
Quevega will defend her crown in the Mares' Hurdle at the Cheltenham Festival, trainer Willie Mullins told race sponsors OLBG.
Emma Lavelle hopes the wet weather forecast is wide of the mark ahead of Claret Cloak's bid to extend the Andover trainer's good form in The Ladbroke at Ascot on Saturday
The five-year-old finished a two-length third to Raya Star over the same course and distance in early November and only carries 3lb more at the weekend. But rain is expected ahead of the race and she said: "I'm not pleased with the forecast, but as long as it's not heavy I'd imagine we'll run.
"He'll probably take his chance because he's got so many things going for him."
