Celtic captain Scott Brown has defended Neil Lennon following his manager's recent criticism of referees.
Scottish Football Association compliance officer Vincent Lunny has written to Lennon for the third time in just over a week.
"You can't say anything about anybody or it goes to the SFA," said Brown.
"It is extremely difficult. If he says one word, it gets blown out of proportion."
The Celtic manager was quoted in the Evening Times saying he hoped for "a decent refereeing performance" for Sunday's visit by St Johnstone.
Lennon is alleged to have breached the SFA's rule 69, which prevents managers commenting on officials before games.
The Celtic boss was quoted talking about Sunday's game, which will be refereed by George Salmond.
"It will be nice just to be able to go out and think only about winning a game of football - and maybe have a decent refereeing performance into the bargain," he is quoted as saying.
Lennon had been served with a notice of complaint by Lunny on Monday after being banned from the dugout by referee Calum Murray at half-time in the 3-2 defeat by Rangers at Ibrox on Sunday.
The Celtic manager described the decision in a game Celtic needed to win to clinch the Scottish title on their rival's ground as "a joke".
Lunny had already written to the Northern Irishman asking him to explain his comments following last week's 1-0 Scottish Communities League Cup final defeat by Kilmarnock at Hampden.
He referred to referee Willie Collum's decision not to award Celtic a late penalty as "shocking" and "criminal".
Celtic have until 1700 BST on Friday to reply with an explanation of those remarks.