Celtic manager Neil Lennon received his third disciplinary notice from the Scottish Football Association (SFA) in just over a week on Wednesday.
SFA compliance officer Vincent Lunny has written to Lennon asking for an explanation of comments the Hoops boss made about referees ahead of champions-elect Celtic's Scottish Premier League match against St Johnstone at Parkhead this coming Sunday.
Ahead of the visit of the Saints, which will be refereed by George Salmond, Lennon was quoted in Tuesday's Glasgow Evening Times as saying: "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."
Those remarks could see Lennon fall foul of rule 69, which prevents managers commenting on referees before games -- a regulation implemented at the start of this season.
The Northern Irishman has until Friday to respond.
The former Celtic captain was served with a notice of complaint by Lunny on Monday after being sent off by referee Calum Murray at half-time in the 3-2 Glasgow derby league defeat by Rangers at Ibrox on Sunday, a decision Lennon labelled "a joke".
Lunny had previously written to Lennon asking him to explain his comments following last week's shock 1-0 Scottish League Cup final defeat by Kilmarnock at Hampden when he referred to referee Willie Collum's decision not to award the Hoops a late penalty as "shocking" and "criminal".
Meanwhile, Lennon threatened to stop using his Twitter account.
Earlier on Wednesday he posted: "Ive best job in the world" (sic) after saying, "enjoy your morning...am going to watch these great young players train...its such a buzz." (sic).
However, his outlook changed during the day and he subsequently tweeted: "Guys enough with the hate and bitterness on both sides..this twitter is supposed to be fun.i will stop unless you stop."
Had Celtic defeated reigning champions Rangers, whose 10 point deduction for entering administration has had a major effect on the title race, they would have won the league last weekend.
But despite that defeat Celtic are still a huge 18 points clear at the top and could lift the SPL trophy this weekend if results go their way.