Trainer Nicky Henderson says he is "desperate" for Sprinter Sacre to return at Ascot on Saturday but is worried about heavy going.
Henderson will declare the horse, who has recovered from a heart murmur, on Thursday for the Clarence House Chase.
But he is conscious the nine-year-old former champion chaser has not raced for more than a year.
"We're desperately keen to run and I think we've got to go positive," Henderson said.
"He has been in heavy ground, it's just not ideal for his first run after all this time off and the speed and the jumping doesn't work quite as well if you can't bounce off it."
Sprinter Sacre was rated one of the best recent steeplechasers, winning races at the 2013 Festivals at Cheltenham (Queen Mother Champion Chase), Aintree (Melling Chase) and Punchestown (Champion Chase).
The horse was pulled up in the Desert Orchid Chase at Kempton in December 2013, and diagnosed with a heart problem.
He was initially rated odds-on favourite for his comeback race, but is now about an 11-8 chance with doubts over his participation.