Only once has the managerial master—I think we can safely assume that Louis van Gaal will not object to such a description—encountered his former pupil in head-to-head competition.
That was in May 2010, when Jose Mourinho’s Inter overcame Van Gaal’s Bayern Munich to win the Champions League final.
And now the theatrically super-confident Dutchman must at least get even with his friend from Portugal if Manchester United are to regain their position as England’s leading club, for Chelsea under Mourinho will surely not fade again as they did toward the end of last season, when the race was left to Liverpool and the ultimately successful Manchester City.
Mourinho always says his second season at a club is the one to watch, and I tend to agree with those who expect him to repeat the two-year timescale taken in building Real Madrid into the Spanish champions of 2011/12.
Chelsea have bought impressively this summer, luring striker Diego Costa and attacking left-back Filipe Luis from Atletico Madrid, and midfielder Cesc Fabregas from Barcelona. Each of these should bring refreshment to the parts of the team that looked in clearest need of it last time round.
City, while adding a much-needed central defender in Eliaquim Mangala, have accepted that Financial Fair Play constrains them from displaying their customary "wow factor" in this summer’s market; Liverpool have lost Luis Suarez; and Arsenal, though their trophy drought ended with the brandishing of The FA Cup, have yet to prove that they can defend like champions. So all could be threatened by a United resurgence under Van Gaal.
But Chelsea? Already I’ve ticked October 26, when they visit Old Trafford, as a date to keep free.
Not that the rivalry—which both Van Gaal and Mourinho insist will be conducted in the spirit of a relationship that grew warm as the younger man learned under Van Gaal at Barcelona—will be kept in check until then.
Hardly a week will go by without it resurfacing; their egos are too big, too hopelessly irrepressible, for that to be possible. Especially as Van Gaal now has the job Mourinho once craved.
There are few managers in the world to whom the challenge of taking over from Sir Alex Ferguson at Old Trafford would not have been daunting. The majority, though they might have denied it, would have been human enough to harbour a fear of the fate that duly befell David Moyes. Not Van Gaal.
Not Mourinho. They talk, behave and appear to believe that even the greatest clubs are lucky to have them.
No wonder they got on in Catalonia, where Mourinho, having been persuaded by Van Gaal not to quit in protest at the effective demotion of Sir Bobby Robson, was encouraged to gain experience at the top end of the coaching trade, working with players as gifted and opinionated as Pep Guardiola and Hristo Stoichkov.
As quoted in my biography of Mourinho, Van Gaal once said: "Jose...was a little bit arrogant, but I like that. I like people with a high opinion of themselves."
The truism that the game of football is about players is, therefore, unlikely to be evident in the forthcoming Premier League contest between these two plain speakers.
If, as looks to be the case, fate and the fixture computer have been markedly kinder to Van Gaal than to his predecessor Moyes last season, United could well be back among the front-runners throughout the 10 weeks leading to Chelsea’s journey up the M6. They kick off the season with a lunchtime match at home to troubled Swansea and then, after a visit to Sunderland, meet the three teams finding their feet after promotion.
Their toughest assignment before facing Mourinho’s men is Everton—and even that’s at home.
So it all fits in rather conveniently with Van Gaal’s assertion that clubs take about three months to become fully attuned to his methods, as per the Express' John Richardson. To judge from highly encouraging pre-season form, his United might be able to make the adjustment while sustaining only light damage. We shall see.
It will also be interesting to discover whether Van Gaal is bent on making an immediate tactical mark on the English game, as Mourinho did with his Chelsea 4-3-3 (featuring Arjen Robben, whose wide attacking was being so vividly employed by Van Gaal in the World Cup only weeks ago) back in 2004/05.
Will United’s three at the back now be all the rage? Already promoted Queens Park Rangers boss Harry Redknapp has called in Glenn Hoddle to supervise a switch to the formation he once used with Swindon, Chelsea and England.
In more ways than one, Van Gaal’s appointment seems certain to signal about the biggest change in the shape of the League this season. And, of course, he’d be the first to admit it.
Patrick Barclay is an award-winning football journalist and best-selling author, whose portfolio includes biographies on Jose Mourinho and Sir Alex Ferguson.