Midway through the first half of Donegal and Kildare's Division One game in Ballyshannon, Kildare captain Eoin Doyle was sent-off.
Doyle had just received his second yellow card of the game. The second of those was handed out by referee David Gough for Doyle not wearing a gum shield.
Eoin Doyle of Kildare is OFF after 2 yellow cards the second for not wearing a gum shield
— Official Donegal GAA (@officialdonegal) February 25, 2018
The wearing of a mouth guard has been compulsory since 2014. Not following the referee's instruction to wear one is a bookable offence.
Speaking to Brian Carthy for RTÉ Radio One after the game, Kildare manager Cian O'Neill was highly critical of how Gough handled the situation.
Accoring to O'Neill, Gough instructed Doyle to put in a gum shield. However, he did not stop the game.
When Kildare keeper Mark Donnellan launched a kick in Doyle's direction as he made his way to the sideline, the centre-back caught the ball. He was subsequently booked by Gough.
"I know exactly what happened because I was there," said O'Neill. "When you think of what happened and the sequence of events, it was just shocking really, disgraceful."
"To be fair to the referee in the first instance, Eoin's mouth guard got knocked out when he got a hard shoulder early on. His mouth guard was knocked out so the referee gave him the opportunity to go to the line to get one but didn't stop the game.
"Eoin was running over to us - I was right beside the linesman - he shouted out, 'Lads, I need a mouth guard'. He was coming over to get his mouth guard and the linesman was well aware of that because he was beside me.
"Then, our goalkeeper didn't realise that. How would he know? Because the referee didn't signal, the linesman said he didn't even know.
The ball was kicked over to Eoin as he was running off the pitch and he just caught it but he was coming over to get the mouth guard and the ref gave him a yellow card for that.
I said it to the linesman, that you should tell the referee that you know he was coming to get his mouth guard.
Zero communication there, which is not good practice in my view. And just to compound that, the referee didn't even realise that he'd given him a yellow card and let play go on.
How many mistakes does it take to get things right? I just don't know anymore.
"If you're going to ask a player to remove himself from the pitch, for whatever reason - blood sub, black card or in this case gum shield - well then stop the game," added O'Neill.
"Let him get off the pitch and then signal to the goalkeeper to continue with the play. To let play continue while the man is running off the pitch... Show me a rule in the rule book where that makes sense."
Donegal won the game by two points - 1-15 to 3-7.
Photo by Stephen McCarthy/Sportsfile