The two Argentines have had meetings before on the touchline and will have another one at Wembley Stadium on Tuesday.
Similarities of Pochettino and Pellegrino on show in Tottenham v Southampton
It can be hard to explain to visitors to England why the day after Christmas is known as Boxing Day.
It is enduringly perplexing to most foreign coaches, who have learned their football in nations where the winter break serves for necessary mid-season physical and mental recuperation, why the period of late December and New Year is the most cluttered of any on the English fixture-list.
Mauricio Pellegrino, of Southampton, is about to experience for the first time as a senior Premier League manager how intense that can be.
And, as his first Christmas holiday match is against the Tottenham Hotspur of his compatriot Mauricio Pochettino, he might be allowed to imagine boxing day is in fact an allusion to the combat sport of red gloves and gumshields.
These two coaches, you see, have a bit of history and the part of it when they previously stood in opposing technical areas was fiery.
A little over five years ago, they met as novice bosses, Pellegrino in charge of Valencia, and Pochettino of Espanyol in the top flight of Spanish football.
The result went Pellegrino’s way, thanks to a hotly contested late penalty, for 2-1 to the hosts. The referee may have felt exhausted by then.
He had issued no fewer than 14 yellow cards, divided equally between the teams, and then a pair of reds to Pochettino’s men, both of them later appealed by Espanyol.
Respect was maintained, at least, along the touchline by two Argentinians united on the day by feeling under pressure and sceptical about the officiating.
“There were too many cards,” said Pellegrino, acknowledging Valencia had the rub of the green to gain their three points. Pochettino remained convinced that Espanyol, at that stage owners of the poorest disciplinary record in the Primera Liga, had turned into “an easy target for refs.” The two Mauricios shook hands, bade each other farewell.
Within two weeks, both men had lost their jobs. So there they were, a pair of unemployed coaches as 2012 turned into 2013, almost exactly the same age – Pellegrino, who turned 46 in October is five months the older – wondering what their next move might be, and little imagining that the next time they crossed would be at Wembley Stadium.
Their careers have had several intersections; the likenesses are many. Apart from their shared nationality, they played in the same position, both tall centre-halves, and for a period, they were in competition for a single place in the Argentina team.
They were colleagues in the same national squad, briefly, at the turn of the millennium. Pochettino got the nod. He won over 20 caps, Pellegrino just three.
They both gained great respect in Spain, where Pochettino had two spells as a defender with Espanyol.
At Valencia, Pellegrino played in Spanish title winning teams in 2002 and 2004 and in two Uefa Champions League finals.
In the second of them, agonisingly, he missed a spot-kick in the defeat via penalty shoot-out against Bayern Munich.
Both men transmitted leadership on the pitch; hence the invitation from the Spanish clubs they had served best as players to come back as coaches.
Pellegrino had an strong backer in the former Valencia coach Rafa Benitez, who gave him a role on the staff at Liverpool as part of his managerial apprenticeship.
But, arguably, it is to Pochettino that Pellegrino owes the greatest debt for his move into Premier League management.
Southampton had done very well out of one young Argentinian manager in the past, and last summer, as they sought a replacement for Claude Puel, they envisaged in Pellegrino’s potential something of what Pochettino had brought to the club when Saints took him out of unemployment less than two months after he had been dismissed by Espanyol.
Pochettino was not a managerial star back then. He is now, three years on from Spurs’ headhunting him from Southampton, where he spent 16 months.
As for Pellegrino, he would hope to be judged on a body of work at least as long as that.
He is not yet half a season into his stint at St Mary’s, and with 19 points from 19 games, a habit of inconsistency and some bland displays, it has not been a straightforward start.
Yet comparisons with Pochettino’s early months in England might feel reassuring. ‘Poch’, who today seeks the win that could push Spurs back into the top four, with striker Harry Kane eager to set a new Premier League record for goals in a calendar year – one more and he reaches 37 - arrived mid-season at Southampton in January 2013.
By the end of that campaign he had won, yes, exactly 19 points for the club where he would go on to develop a glowing reputation.