For a manager who is commonly thought to be incapable of building a dynasty, José Mourinho left a remarkably durable legacy in his first spell at Chelsea. Neither party, it seemed, could ever quite let go. Even as late as 2012-13 Mourinho was referring to Chelsea's squad as "my players" which, to an extent, they were.
Managers as diverse as Carlo Ancelotti and André Villas-Boas could not escape the Mourinho blueprint. One of the great ironies of Roman Abramovich's first decade as Chelsea owner is that his relationship with Mourinho soured as he began to sign un-Mourinho-like players and yet, once he had gone, he continued to follow the Mourinho formula.
Chelsea's eventual victory in the 2012 Champions League came after victories over Barcelona and Bayern Munich that, from a tactical point of view, were almost like parodies of Mourinho schema.
And then, just as Rafa Benítez seemed to have broken the spell, just as he had ended the dependence on the old guard, Mourinho returned. It was like Heathcliff taking control of Wuthering Heights once again. There was one glorious high and then a second, crushing end to the affair. Perhaps Mourinho's influence will not prove so enduring second time round – although given the way the Stamford Bridge crowd turned on the "rats" who had supposedly betrayed him and chanted his name after his sacking last season, it is safe to assume he will receive a warm welcome on Sunday when he visits in charge of Manchester United.
Perhaps the knowledge of how badly the second attempt turned out will stifle any enthusiasm to try for a third time.
Perhaps the sight of him in the arms of another Premier League club will dull the ardour. But even if the grip of Mourinho proves less persistent this time round, Antonio Conte's first major task is to move the club on, to make sure they – players, directors and fans – are committed to him and not their former manager.
In one sense it should be easier. Not only does Conte have boundless energy and a potent charisma but this group of players has nothing like the affection for Mourinho that Frank Lampard, Petr Cech, Michael Ballack and Didier Drogba did.
Even John Terry’s relationship with Mourinho seemed to have cooled by the time Mourinho departed last December.
Conte is unlikely to find many of his present squad in regular text conversations with their former manager.
But on a broader level the problem remains. This is still a squad built to his template.
The players Conte inherited had been assembled to play either a 4-3-3 or a 4-2-3-1, with the back four sitting deep. Previous attempts to introduce a high line, most notably under Villas-Boas, had faltered, largely because of Terry. His performance in the 5-3 home defeat by Arsenal in October 2011 was a case study in the dangers of asking a defender who lacks pace and is slow on the turn to operate high up the pitch.
Yet Terry remains Chelsea's best natural defender. He is still, even at 35, one of the best centre-backs in the league. The problem is that Conte, at Siena, at Juventus and with Italy, has always favoured a high line. That's what made the decision to give Terry a one-year contract extension so intriguing. Conte began the season trying to compromise, using the 4-2-3-1 that had been bequeathed to him. The side he sent out against West Ham on the opening weekend featured only one change from the team Mourinho had sent out against Swansea on the opening weekend last season.
But after the draw at Swansea and the defeats by Liverpool and Arsenal – and the 4-2 League Cup win over Leicester – he has returned to what he knows best. With Terry injured he has turned to a back three, using Victor Moses and Marcos Alonso as wing-backs. It is not clear whether there is any place in such a structure for Terry. What is clear, though, is that performances have improved significantly, albeit only in wins over Hull and Leicester.
Chelsea’s back three, in its present guise, feels like a temporary solution, something Conte has patched together from imperfect materials. If they perform well against United that perception may change.
But that Conte has made the shift at all is significant. This is a key step in placing his own stamp on the club. And, of course, there could be few better ways for Conte to assert himself than to vanquish his predecessor on Sunday – particularly if he does it with a team set up in what is recognisably his way.