Star jumper Altior has failed to recover from injury in time for the Queen Mother Champion Chase at Cheltenham.

Trainer Nicky Henderson announced on Sunday morning the brilliant two-miler was lame, after a dormant splint that had never caused a problem to the 10-year-old previously "reared its ugly head".

The situation had improved markedly on Monday, and he was declared for the race at the 48-hour stage, although Henderson stressed more progress was needed and that he would not have run if the race had been then.

"What is really disappointing is the improvement from the night before last to yesterday morning was so good that we were genuinely optimistic that, as long as that recovery rate was maintained, we figured he'd be sound this morning, and that is not the case," Henderson said.

"It's flattened off - he hasn't improved at all from last night, whereas the night before he improved dramatically.

"Consequently, I think it's only right now that he will be taken out of the race."

The Philip Hobbs-trained Defi Du Seuil is now favourite for the race on Wednesday (Thursday AEDT).