The complexion of the Betway Queen Mother Champion Chase at Cheltenham has completely changed after Altior was "lame this morning in his near fore leg", but trainer Nicky Henderson remains hopeful he can run in the big race.
Douvan will be in the race rather than the Ryanair Chase after final declarations came through this morning, with Ruby Walsh booked on board.
Trainer Willie Mullins and owner Rich Ricci had suggested on Sunday they might avoid a clash with their other hope, Min, and wait for Thursday's race, but that will not be the case.
Paul Townend will ride Min.
Douvan does have a point to prove as he has been out of action since disappointing in this race 12 months ago, when sent off the 2-9 favourite.
And if Altior is indeed out of the race, it is set-up for Mullins to have the two top in the betting for the race.
Trainer Nicky Henderson said he will have a more definitive idea of whether or not he runs at Cheltenham on Tuesday morning.
The Seven Barrows handler said in a statement posted on his Twitter account: "Altior was unfortunately lame this morning in his near-fore leg and we have located some pus in the frog (of his foot).
"He was still able to exercise in the water treadmill this morning, which he regularly does anyway, and a poultice will now be applied and left on overnight to draw out the pus.
"The foot will also be 'tubbed' (stood in salt water) at regular intervals and the shoe will hopefully be replaced first thing tomorrow morning.
"Both our vet and farrier are working very hard and are more than hopeful that he will even be able to canter tomorrow and therefore confident he will be clear to race on Wednesday.
"Obviously we will monitor the situation and keep everybody up to date with his progress, but there will nothing more to say until tomorrow morning."