Whilst Pep Guardiola is currently being lauded for modernising English football, there are fears that Mourinho is sowing the seeds for bitterness and resentment between England stars for years to come.
Back when Spain dominated world football, Mourinho's actions caused such animosity between Real Madrid and Barcelona that players from the two sides were reluctant to speak to each other on international duty as they looked to prove their loyalty to their clubs.
This completely went against the team spirit that Vicente Del Bosque was trying to foster in the squad and the experienced boss has since gone on record praising Iker Casillas for his role in controlling the tensions, though whether that contributed to him being cast aside by Mourinho is a debate for another day.
'It’s true that in difficult moments for the national team, when the Real-Barca games got a little bit strange, Casillas helped the team move on. He was a key figure in fostering harmony,’ Del Bosque explained.
‘This did not go down well [with Mourinho] and perhaps also had a detrimental effect on Iker.’
Now there are concerns that Mourinho could be set to create a similar war between Manchester United and Manchester City, something which could seriously damage England going forward.
Each Manchester side has six players that could potentially be involved at next summer's World Cup (Marcus Rashford, Jesse Lingard, Phil Jones, Ashley Young, Chris Smalling and Luke Shaw for United and Kyle Walker, John Stones, Raheem Sterling, Fabian Delph, Phil Foden and Joe Hart (on loan at West Ham) for City), meaning that a full-on rivalry could prove costly to team morale.
The tunnel bust-up following last weekend's Manchester derby was the latest sign that Mourinho may already be turning to the 'dark arts' of football in a bit to gain ground on City and whilst it is not clear whether any England players were involved in the spat, there will certainly be concern at FA HQ that club rivalries could damage England's prospects going forward, particularly in the wake of Rio Ferdinand's recent relevations.
The former Manchester United defender told 'BT Sport' recently that he felt that club loyalties had impacted England's so-called 'Golden generation'., preventing them from ever reaching their potential.
‘I didn’t want to sit around and have a beer with Steven Gerrard because I didn’t want to hear what Liverpool were doing, I think that’s what held us back [with England],’ he said.
‘I came through at West Ham with Frank [Lampard], we were proper mates. Then I left and went to Leeds then Manchester United, Frank went to Chelsea and around that time our communication just disintegrated. It was down to, from my perspective, the obsession with winning. I didn’t want to see Frank have an edge on me.’
However, City winger Raheem Sterling recently said that the atmosphere with England is the best he has experienced since making his debut five years ago.
‘When I first went in compared to now it’s amazing. Really friendly,’ he said.
‘I’m in Marcus’s [Rashford] room, playing Call of Duty with him and Jesse [Lingard], then I’m playing FIFA with Dele [Alli] next door. Then I’ll be with John [Stones]. Really, everyone’s friends with everyone, it’s good to see.
‘People would talk to each other before but now you can see that every player is with everyone. There are always little sessions going on — it’s really good.’
Nevertheless, with Mourinho likely to stop at nothing in his quest to overhaul City between now and May, English football's bigwigs will be hoping that no relationships are harmed beyond repair.