JCB Triumph Hurdle fancy, Cliffs Of Dover, is doubtful for Cheltenham, trainer Paul Nicholls revealed on Tuesday.
Formerly trained by Charlie Hills on the Flat, this son of Canford Cliffs has been a revelation since joining Nicholls, winning six of his last seven outings over hurdles.
This four-year-old is fancied for the Triumph Hurdle but his participation could be in doubt after taking a knock while schooling.
Nicholls, who trains the 140 rated gelding for John Cotton and his wife Barbara, said: "I schooled him just before he was going to go to Musselburgh last week and he knocked himself. It might just be a race against time to get him there. If he doesn't come right he might have to go to Aintree."
Better next season
Nicholls' added: "He's won six - I suppose we've placed him well - but he's a good horse.
"If we'd known more about him he wouldn't have been beaten at Market Rasen - we rode him wrong that day. He's a good horse and if we can't quite get him right this season for whatever reason he'll be better next season when he'll be a really good hurdler.
"He wants looking after and we could do with a few more like him."