Neil Lennon and the Scottish Football Association are on course for yet another collision after the Celtic manager described his sending off at half-time at Ibrox as "a joke" and claimed he was "deprived of doing my job properly" during the 3-2 defeat to Rangers.
Celtic were odds-on to get the win required to clinch the Scottish Premier League title, but Sone Aluko scored a marvellous solo goal in the 11th minute to spark another afternoon of Old Firm drama.
Lennon was raging when Hoops defender Cha Du-Ri was sent off by referee Calum Murray in the 28th minute for a challenge on Lee Wallace.
The Celtic boss spoke to Murray going up the tunnel and was then called into the official's room where he was sent to the stand, although he said he had to watch the second half from the media room "for my own safety".
Celtic midfielder Victor Wanyama was sent off for a two-footed tackle on Steven Whittaker before goals from substitute Andy Little and Wallace put Rangers 3-0 ahead, with a Scott Brown penalty and a Thomas Rogne injury-time header reducing the deficit - but not the ire of the Parkhead manager.
Lennon, who has been asked by the SFA's compliance officer, Vincent Lunny, for an explanation of his criticism of referee Willie Collum following last week's 1-0 League Cup final against Kilmarnock at Hampden, said: "The first one is not a sending off and the second is borderline probably, you can't tackle like that.
"My sending off is joke. I don't think I deserved to be sent off. My staff are very angry about it, my players are angry and disappointed. I spoke quite quietly and coldly to the referee in the tunnel. I didn't swear and didn't point any fingers.
"I told him I wasn't happy with his first-half performance. I was speaking to the match delegate after the game and their version of events are different from mine but I've got witnesses to back me up.
"Alan Thompson (coach) and our PR person was there, a couple of other members of staff and players. I do my team talk at half-time, I walk back out and got called into the referee's room. I have been deprived of doing my job properly when my team needed me. I am very angry about that."
Lennon was also angry that he was prevented from sitting in the stand.
"That's another thing," he said. "I can't sit in the stand for my own safety - that sums things up in this country. I would have sat in the directors' box but I was told for my own safety that it wasn't a good idea. I watched the second half in here (the media room).
"The biggest game of the season and I can't go out in the stand to watch my team or send down messages. I have Stevie Woods (goalkeeping coach) at the door and he was running up and down the tunnel for me. I might as well have sat in the house and watched the second half.
"When you are down to nine men, it is an uphill task. This is not the first time we have come to Ibrox and had players sent off for little or nothing.
"So today has been soured. I congratulate Rangers on their win, I haven't got a problem with that, but there are mitigating circumstances in why they have won."
Lennon continued his rant against referee Murray, adding: "I wanted to see him after the game and I got a message back to wait 20 minutes later then I could go and see him - 20 minutes later he wouldn't see me.
"So who is accountable? Why don't I get an explanation? I have to be very careful what I say but I want some answers and I'm not getting them. As manager of the football club I think I deserve that."
Speaking about Cha's dismissal for hauling back Wallace - which he claimed "changed the game" - Lennon added: "I can't for the life of me see how that is a red card.
"He's going away from goal, he's not going to get the ball and Charlie Mulgrew is getting over. Their second goal is offside, Wallace is in an offside position (before his shot is saved by Fraser Forster), so the linesman has not done his job properly.
"We scored two goals and that sums up our players - they keep going until the final whistle, even with nine men. I am very proud of the players and supporters."