Over the years, as the relationship between Arsene Wenger and Jose Mourinho soured, it has become clear that the pair cannot stand to be in the same room.
The post-match ritual, with the host manager inviting coaching staff from the opposition into his stadium office for a glass of wine and a finger buffet, is now habitually snubbed by Wenger and Mourinho, home or away.
Less than 48 hours after they childishly manoeuvred their way around the technical areas at Wembley in an attempt to take the moral high ground, they will come face to face again.
For two hours on Tuesday afternoon, between 3pm and 5pm, the pair have been forced into the same conference room by the Premier League for the annual managers’ summit. At best it will be civil. The meeting at the PL’s Gloucester Place headquarters in London is mandatory, although they have allowed Tottenham’s Mauricio Pochettino to be absent because Spurs are playing in Munich.
On another occasion, when all 20 managers arrived for one of their meetings to discuss rule changes and chit-chat about other items, the best they could apparently do was to eyeball each other.
There is a stubborn refusal to budge, and in the aftermath of Arsenal’s 1-0 victory in Sunday’s Community Shield, both sides insisted the relationship is unlikely to recover.
Oddly, Mourinho has always been preoccupied with Wenger, continuing to pick away at his record at Arsenal with a series of deliberately timed attempts to destabilise his position at the Emirates.
Mourinho is motivated by feuds with rival managers and has picked fight after fight down the years with Pep Guardiola, the late Tito Vilanova, Rafa Benitez and Wenger. Only last week Mourinho responded to a joke made by Benitez’s wife Maria about her husband ‘clearing up the mess’ left by the Portuguese coach at Chelsea and Inter Milan.
The attack that followed was unnecessary and certainly not becoming of a manager who last season won the Premier League title for the third time in his career at Chelsea.
He moved swiftly on to Wenger after that, choosing his words carefully in the build-up to Sunday’s Community Shield against their London rivals.
For once, perhaps Mourinho spoke too soon.