Two-time champion chaser Altior has been ruled out of this week’s Cheltenham Festival.
The 2018 and 2019 winner was also a late withdrawal from the Queen Mother Champion Chase last year.
Trainer Nicky Henderson withdrew the horse after he was found to be coughing after exercise on Monday morning.
Henderson said it was a “bitter blow” to the team and “heartbreaking” to be unable to run Altior at Cheltenham for the second year in a row.
It is hoped that the 11-year-old can still compete this season after Henderson confirmed that the horse was suffering from an infection.
He said: “It appears we are dealing with a bacterial infection rather than a viral infection.
“It’s cruel on everybody. There certainly wasn’t anything wrong with him on Friday, so it’s a recent thing. For it to happen two years running is cruel for the owners.
“We might get him back for something this season yet.”
Chacun Pour Soi is now odds-on to give Irish champion trainer Willie Mullins his first Champion Chase triumph.