The Scottish government is warning that it could call a halt to the football season after a Celtic player breached coronavirus rules.
Boli Bolingoli admitted he played in Sunday's match against Kilmarnock despite having recently returned from Spain without quarantining.
The defender said he was "guilty of an error of judgement" and apologised.
The breach comes after eight Aberdeen players apologised for visiting a bar at the centre of a Covid-19 outbreak.
Two of the players later tested positive for the virus, while six are currently self-isolating.
In a statement, Bolingoli said he wanted to apologise to his manager, team mates, supporters, "and so many others for letting them down so badly".
'What I did was wrong'
He added: "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."
Celtic FC said a full investigation was under way into the incident .
The club said it took its response to Covid-19 "extremely seriously" and that, to date, it had not recorded any positive tests.
In a statement, the Scottish government said it was aware of reports of the player having broken quarantine rules last week.
It added: "We are currently in discussion with the club and football governing bodies to establish the facts.
"If confirmed as another serious incident within Scottish football, where protocols have been breached at the risk of wider public health, then the Scottish government will have little choice but to consider whether a pause is now needed in the resumption of the game in Scotland."