Altior will not run at the 2021 Cheltenham Festival, trainer Nicky Henderson has confirmed.
The winner of the Betway Queen Mother Champion Chase in 2018 and 2019 was taking on hot favourite Chacun Pour Soi in his hat-trick bid.
However Henderson has had to scrap those plans, a day before the start of the meeting on Tuesday.
"We are very sorry that we have taken the difficult decision not to run Altior in the Champion Chase on Wednesday," he tweeted.
"He coughed after exercise this morning which caused us to scope him and as a result of what we have seen it would not be sensible to run him.
"This is devastating for all of us, and Pat and Christopher Pugh in particular, in that this is the second year running we have had to pull him out at the last minute."
Jonjo O'Neill also had to pull one of his key horses out of an intended race.
Annie Mc, a mare co-owned by reality star Chris Hughes, misses the Mrs Paddy Power Mares' Chase on Gold Cup day.
O'Neill said: "Sadly Annie Mc has suffered a small setback and will not run in the Mares’ Chase on Friday.
"Unfortunately Cheltenham has just come a week too soon for her."
