What happened towards the closing stages of extra-time in the Carabao Cup final was truly remarkable.
Chelsea and Manchester City were heading for a penalty shootout when Kepa Arrizabalaga was treated for cramp.
Maurizio Sarri turned to Willy Caballero and the reserve goalkeeper prepared himself to come on.
But Kepa resisted Sarri’s attempts to bring him off, wagging his finger and shouting “NO!”, and stayed on the pitch.
Referee Jon Moss ran over to Chelsea’s bench to confirm what was happening and Sarri eventually relented, allowing Kepa to remain for the shootout.
The Spaniard went on to save Leroy Sane’s effort but Man City eventually secured a 4-3 shootout win thanks to Raheem Sterling’s strike.
Now, attentions turn to Chelsea and whether a punishment awaits Kepa.
Clattenburg: Jon Moss can’t be blamed
It’s an incident that nobody will forget in a hurry and that includes Moss and his assistants.
Both Kepa and Caballero’s numbers had gone up on the board to indicate the substitute and some will argue that Moss should have been firmer and told Kepa to leave the pitch.
But former Premier League referee Mark Clattenburg believes no blame can be attributed to Moss.
Clattenburg explained the rules in a Daily Mail column, insisting that the numbers going up are simply a guide and do not mean the substitute is official.
“While the Kepa situation was farcical, no blame could be attached to referee Jon Moss or his assistants,” Clattenburg said.
“A substitution is only deemed to have happened when the oncoming player crosses the outgoing player on the touchline and the referee has restarted play. Until then a manager is free to change their mind.
“The numbers being held up are simply a guide – but do not mean the substitution is irreversible.
“If a keeper is injured during a shootout he can be replaced by a sub – as long as all that team’s substitutions have not been made.”
Moss spoke to Kepa before he went over to Sarri, but he clearly didn’t tell the former Athletic Bilbao ‘keeper that he had to leave the pitch.
It was left to Kepa and Sarri to sort out, and it was the player who won the tussle.