Big Buck's and Al Ferof out for season
Big Buck's and Ruby Walsh
(Healy Racing Photos)
The former was due to run in Saturday's Long Walk Hurdle at Ascot, while Al Ferof was being prepared for an assault at the King George VI Chase at Kempton on Boxing Day.
Nicholls told Betfair: "At evening stables tonight, we discovered a problem with both Big Buck's and Al Ferof.
"I am not in a position to go into great detail at this point, but I can confirm that Big Buck's will not be taking up his engagement at Ascot on Saturday and Al Ferof will not be running in the King George.
"And both are unlikely to run again this season."
Big Buck's owner Andy Stewart later confirmed that his horse has suffered a leg injury.
Rubi Light was suffering from a lung infection when he trailed home a well-beaten third behind Flemenstar and Sir Des Champs in the John Durkan Memorial Punchestown Chase.