Neil Lennon is incensed by the behaviour of Boli Bolingoli and his quarantine breach could spell the end of his Celtic career, according to The Scottish Sun's Robert Grieve.
Bolingoli has prompted a mass review into the feasibility of the Scottish season going further, after he breached quarantine rules by going on holiday to Spain.
"I have made a huge mistake. I want to apologise to my manager, my team-mates, the supporters, everyone at Celtic and so many others for letting them down so badly," Bolingoli said.
"I am guilty of a major error of judgement. I know what I did was wrong and I know that I must now deal with the consequences."
Grieve, chief football writer at The Scottish Sun, believes that the apology will likely not be safeguard his Celtic future.
"I genuinely cannot remember hearing Neil Lennon as angry as he was today. He was really let down by Bolingoli, and completely flabbergasted by the situation.
"You have to ask yourself: what more can Celtic do? They make it perfectly clear what the situation is. These guys are in a bubble - and yet something like this happens.
"It beggars belief."
The Bolingoli situation comes soon after Aberdeen players being found to have gone for a meal and drinks following a match with Rangers, heightening fears of transmission.
"[The Aberdeen incident] was stupidity, gross stupidity. But this is on a different level; this is a player going abroad, who doesn't have any thought for anybody but himself.
"He doesn't care about the consequences. The Aberdeen thing was just stupidity, this goes way beyond that.
"Neil Lennon doesn't just write this off as a daft football player. This was a guy that made a conscious decision that he was going to go abroad for 24 hours with his girlfriend, and to hell with the rest of it."
Grieve has sympathy for the situation the club find themselves in.
"Celtic were completely and utterly unaware of this situation until we approached them with it - and now Lennon is having to face the music this afternoon.
"I don't think that there is any way back for Bolingoli after this. He cost them nearly £2m, and he made 14 appearances last season. He has done next to nothing to justify his place at Celtic, and then he has done this."
As to what this means for the prospects of Scottish football continuing, Grieve does not believe it is terminal - yet.
"Scottish football has been given real leeway to get back going again. Clubs were arguing desperately to get going again.
"We are hoping that we can get fans back into grounds in September, no doubt that will get pushed down the road.
"There is no doubt that government has a firm view on Scottish football now - and it is right to do so."