Footage has emerged online showing a fierce exchange between Philippe Clement and Scottish Cup final fourth official Steven McLean.
A clip - visible in Celtic's 'Unique Angle' video - has revealed a tense handshake between the Rangers manager and the Scottish FA official at Hampden.
McLean had been tasked with keeping both Clement and Brendan Rodgers in check as the fourth official for the showpiece final at the national stadium.
However, he received an earful from the Ibrox manager at full-time with Clement clearly unimpressed by the officiating.
The short shot shows Clement shaking hands with McLean - who looks off in the distance - while making his feelings clear in a tense exchange.
McLean appears to remain silent while Clement makes comments during the handshake before responding to the Ibrox boss as they headed in separate directions.
The official then continued to shake hands with players and coaches as Celtic celebrations kicked off at Hampden.
Clement admitted his frustration over the decision to disallow Abdallah Sima's goal in the final for a push on Joe Hart - spotted by VAR official John Beaton.
But Clement conceded the matter was a "grey area" as he commented on Nick Walsh's "really big call" in the final.
On the disallowed Sima strike for his side, Clement commented: "If you have the scenario also that you score goals and they are disallowed in that way, that is also in that moment a disappointment.
"If I compare with the push that Scales gave to Dujon Sterling in the first half, it's a much bigger push than what happened with Joe Hart today.
"If I see also how all the Celtic defenders are grabbing my players and having their arms around their neck and around their waist...it's a really big call to make to disallow the goal."
Asked whether he had discussed the matter with Walsh after the major flashpoint, the Ibrox manager added: "Nothing special. It is their decision. They are honest, they make their decisions.
"It is a grey area that one, it is not white or black so they make their decision.
"Of course, as a manager, you are disappointed about that after the game."
Clement was then furious with Todd Cantwell as he shoved the midfielder away from referee Walsh at full-time.
