The grey's National price was reduced to 12-1 favourite from 16-1 by Coral. The same bookmakers shortened Charlie Brooks' horse to 20-1 from 33-1 for Cheltenham after his owner Andrew Cohen confirmed that he hoped Suny Bay would run in both races.
Ladbrokes offered Suny Bay at 9-2 favourite (from 12-1) for the Hennessy Gold Cup at Newbury a week on Saturday.
Coral also cut yesterday's Haydock runner-up General Wolfe to 33-1 for the National after an encouraging run. Third-placed See More Business is now 33-1 from 50-1 for the Gold Cup.
Peintre Celebre's win in the Prix de l'Arc de Triomphe earned the colt the Cartier Horse of the Year title last night. At a ceremony in London, the Daniel Wildenstein-owned colt beat Pilsudski, Singspiel and Spinning World to claim the award. Xaar took the honours as the top two-year-old colt.