Blackburn boss Sam Allardyce is undergoing surgery on a coronary artery, assistant manager Neil McDonald has confirmed.
Allardyce requires an angioplasty – which involves inserting an artificial tube to widen the artery.
The club hope to have him back at work early next week.
“We wish him well and hopefully Sam will get back as soon as possible,” said McDonald.
“I spoke to him this morning just before they whipped him down. He has gone down and we will find out this afternoon how he is and how quickly he is going to recover.
“He seemed very good and aware of what was happening. We were trying to cheer him up and he is obviously worried because of the operation that he is going through.
“But he probably knows more than the surgeon at the moment. He likes to know what is going on and how things are done, and it keeps it clear in his mind.”
Allardyce missed Sunday’s victory over former club Bolton and the 3-0 defeat by Fulham on Wednesday.
McDonald will take charge of first team affairs until Allardyce returns, which is expected to be for the Carling Cup quarter-final with Chelsea on 2 December.
“I’m sure he’ll be fine, up and about this afternoon and hopefully out tomorrow,” added McDonald.
“If there are any little complications then obviously Wednesday might came a little bit too soon for him, but we are all expecting him back next week.”