Interim boss John Kennedy claimed referee Willie Collum denied Celtic a clear-cut penalty in their 1-1 draw with champions Rangers at Parkhead.
Hoops attacker Mohamed Elyounoussi headed in an Odsonne Edouard cross in the 23rd minute of the Scottish Premiership encounter but minutes later the French forward was booked for diving in the box after a challenge by Gers defender Borna Barisic.
Alfredo Morelos levelled in the 38th minute with his first goal against Celtic and, although the home side had the best of the game, Steven Gerrard's men made it 33 league games unbeaten to keep the 20-point gap between the teams intact.
Kennedy said of the penalty claim: "It had a massive say in the game. I've seen it back and I've spoken to Odsonne.
"If you get any sort of contact in the box, when a player comes flying at you at that speed, comes recklessly in, knocks you off balance, touches you enough to go over - that's what happened there.
"If he doesn't go over, he is on the ball, he scores the goal.
"There is no need for him to go down, he is a goalscorer, he wants as many goals as possible. He is not that type of player.
"I haven't had a chance to speak to the referee. In games like that, these decisions are massive, really important.
"Willie will have his opinion on it, other people might think differently but we are sure it's a penalty.
"So we feel aggrieved that we didn't get a penalty kick, we have to accept that and look at the bigger picture of the performance which was good.
"It was a high level performance. I thought we were dominant most of the game and scored a really great goal, which we were pleased with and disappointed with the goal we conceded. Overall pleased, and the attitude was terrific."
The Celtic players put Old Firm rivalries aside before the game. Rangers players had decided not to take the knee before kick-off in support of Gers midfielder Glen Kamara and the Celtic players did likewise.
The Finland international claimed he had been subject to a racist slur by Ondrej Kudela during the Europe League defeat by Slavia Prague at Ibrox on Thursday night.
Celtic skipper Scott Brown had a quick word with Kamara in the build-up and substitutes, management and backroom staff of both clubs stood along the touchline in a show of solidarity.
Former Celtic defender Kennedy said: "It is important. This is not about derbies, rivalry, opposition.
"This is about unity coming together, and trying to make a difference.
"It has gone on too long. It seems to happen more and more even though there is more education.
"It is not acceptable. You give someone, or whoever it may be, a punishment for it and that will quickly eradicate it."
Gerrard was pleased to see Colombia striker Colombia striker Morelos get his first goal against Celtic at the 15th time of asking.
He said: "I think it will be relief for him, first and foremost.
"He has had a lot of attempts to try and score here so for his own personal point of view, a positive moment for him and it helped us get a decent result.
"He has been magnificent in terms of his contribution, certainly of late, he has scored big goals at key times. So we are really happy with Alfredo.
"Normally he is travelling all round the world for internationals but he is staying behind and he will get some time with his family and be ready for the next game."
While Rangers are only five league games away from being unbeaten through the whole league season - as Celtic did in 2016/17 when they won the domestic treble - Gerrard described it a "sideshow".
He said: "We know people are talking about it on the outside.
"I will give you a little glimpse of what is on the inside - it is all about the next game. It is a sideshow really.
"We will try to do it, we will do everything we can and that means we want to try and win every game. It will be tough, there are a lot of challenges out there.
"The priority now is the Scottish Cup, we want to try and do a double, try to win another trophy but it is also an opportunity for us to try certain players and try different things, give people game time. We will try and get both right."
CELTIC: Bain, Kenny, Welsh, Ajer, Laxalt, Brown (Soro 88), McGregor, Christie, Turnbull (Forrest 79), Elyounoussi (Rogic 85), Edouard (Griffiths 89).
Subs Not Used: Barkas,Taylor,Duffy,Bitton,Klimala.
Rangers: McGregor, Balogun (Patterson 56), Goldson, Helander, Barisic, Kamara, Davis, Aribo (Wright 77), Hagi (Arfield 65), Morelos (Roofe 77), Kent.
Subs Not Used: Bassey, Defoe, Itten, Zungu, McLaughlin.
Referee: William Collum (Scotland).
Man of the match: Odsonne Edouard
Match rating: 7/10