Mauricio Pochettino remembers small kindnesses: when Diego Maradona immediately knew a young Poche's name; when Dejan Lovren gave him a watch accompanied with a note reading, "For my footballing father"; when Harry Kane footed the bill for a Tottenham team meal behind his back.

And when Jose Mourinho invited him to the Bernabeu. Pochettino has not forgotten the Real Madrid coach welcoming him into his office shortly after the Argentine had taken charge of Espanyol in January 2009.

The two bonded over their mutual enmity for Barcelona, who were on the way to an historic treble, and their shared belief that Pep Guardiola, then the Barca coach, was earning too much credit for their success.

"He was a reference when I started my career at Espanyol. He was always very kind to me and opened his door," Pochettino has said of Mourinho, whom he described as "the best manager in the world" on Tuesday.

When they first met, Espanyol were no threat to Real in La Liga but nine years later Pochettino and Mourinho meet on Wednesday as equals when Pochettino's Spurs host Mourinho's Manchester United in a crucial Premier League match at Wembley.

Although they are now direct rivals, they remain close. Before Spurs beat United 2-1 in the final game at White Hart Lane, Mourinho visited Pochettino in his office and they spent time discussing their Premier League competitors. When the Portuguese's father died in the summer, Pochettino called him and the pair exchanged a series of text messages.

Mourinho has no shortage of detractors but Pochettino knows what makes him tick, so much so that Alvaro Morata, the Chelsea striker, rang Pochettino while he was at Real Madrid B to ask how he could impress the first-team coach.

Pochettino does not gush about Mourinho but nor he does not hide his admiration, and he is notably more positive about the 55-year-old in public than his other rivals.

For Pochettino, Guardiola is always "Guardiola", Jurgen Klopp is "Klopp", Arsene Wenger is "Wenger", Antonio Conte is "Conte". But Mourinho is "Jose". Pochettino has even used Mourinho's self-given moniker "The Special One".

Jose Mourinho (left) and Mauricio Pochettino (right) remain good friends despite the rivalry between their clubs. Photo credit should read OLI SCARFF/AFP/Getty Images

During Tottenham's title challenging season of 2015-16, Pochettino was nothing but respectful to Leicester manager Claudio Ranieri, spurning all opportunities to pressure the Italian and his team, or criticise their Premier League rivals who were publicly championing the Foxes' "fairytale", despite his private frustrations.

Pochettino's refusal to vent was possibly a contributing factor as Spurs lost their heads in the infamous 2-2 draw at Chelsea and imploded in the final two matches of the season after Ranieri's Leicester had been confirmed as champions.

Since then, Pochettino -- who had no need to play managerial mind games at either Espanyol or Southampton -- has been much more willing to needle. Last week, he reminded Wenger to focus on Arsenal after the Frenchman indirectly aimed a barb at Spurs and he has said the same to Chelsea coach Conte on more than one occasion.

Pochettino has also questioned the touchline antics of Klopp, the Liverpool boss, and in October he launched his most stinging attack, accusing Guardiola, now at Manchester City, of "sad" and ungentlemanly behaviour for describing Tottenham as "the Harry Kane team". Pochettino hoped his comments would unsettle Guardiola and his title favourites, then just five points ahead of Spurs.

The closest he has come to a dig at Mourinho, though, was in his book, 'A Brave New World', when he accused him of putting Eric Dier in a "compromising position". Even then, it read more like a lesson for Dier than a criticism of Mourinho. In solidarity with Mourinho, Pochettino has even turned down the chance to praise Luke Shaw, who has described the former Southampton boss as a father figure, when the left-back was being frozen out at Old Trafford.

"Not my player, not my problem," was all Pochettino said.

As a former player and an adopted son of the city of Barcelona, Pochettino has far more in common with Guardiola than Mourinho but his issues with the Spaniard run deeper than club rivalry in Spain and England, while he genuinely likes the Portuguese.

Pochettino, however, has described Mourinho as the "master of controlling the public message" and he may simply feel that an attempt to play mind games with the United boss would not turn out favourably.

In terms of philosophy, Pochettino is poles apart from Mourinho -- who will attempt to stifle Spurs' positivity at Wembley with a pragmatic approach -- but the 55-year-old has managed Real and United, two super-clubs that admire Pochettino.

Mourinho would be able to give the Argentine valuable insight into life in both Manchester and the Spanish capital, should he ask over a bottle of wine after Wednesday's match. It is possible these links are another reason that Pochettino has kept his rival on side.