Pep was still the hearbeat of Barça's midfield and Jose was assistant to Bobby Robson and then to Louis van Gaal.
They look close in the photograph and they were. Mourinho was popular with the players: he was charming, didn't take himself too seriously, he evidently had a fine football brain - qualities appreciated by Guardiola.
The fondness was mutual, not for nothing did Mourinho want Guardiola as his No. 2 when he auditioned for the Barcelona job with a Powerpoint presentation to the club's directors Tkiki Begiristain and Marc Ingla in 2008.
The two men won trophies together and when they beat Paris Saint Germain in Rotterdam in the 1997 Cup Winners Cup final they embraced on the pitch, jumping up and down in jubilation, a moment Mourinho would remember years later once installed as Real Madrid manager in the opposite corner to Pep.
"I still have a photo of that embrace," he said. "We were close."
The closeness was another reason it hurt Guardiola all the more when things turned as ugly as they did during their two seasons spent as Barcelona and Real Madrid managers.
That's why when ahead of the first leg of Real Madrid and Barcelona's Champions League semi-final in 2011 Pep ranted: "In the press room, he is the boss, the one who knows more than anyone else." He also said: "I just want to remember that we were together for four years. He knows me and I know him."
Mourinho had started that particular row sarcastically suggesting that Guardiola was breaking new ground by criticising referees even when they were right.
Mourinho's comments came in the middle of a five-game period of Clasico meetings in the cup, league and Champions League. The Barca players had been watching Mourinho's press conference in their Madrid team hotel. The television had been turned up. And their manager had been pushed over the edge.
Guardiola responded in that 45-minute rant, but he had also wanted to remind Mourinho of how close the two had been.
Speaking about the Madrid press that he believed had fed the fire of the pair's feud he added: "If he wants to pay more attention to them than to the friendship, well maybe not friendship, but relationship that we had then he is perfectly within his rights to do that."
As well as being furious at the smear on Barca's ability to win without help from referees or lose without blaming them, he felt he'd been slighted by, if not an old friend, then certainly a fondly-remembered acquaintance.
With his going to war hat on Mourinho had little time for nostalgia. Pep was beating him on a regular basis and has done so consistently since they stopped working together at Barcelona.
Not only did Guardiola dominate Mourinho's Madrid having been given the Barça job ahead of him but he was also offered the Chelsea job ahead of Mourinho who only then landed it because Pep said no.
Even the Manchester United job has come Mourinho's way after United failed to do what most of their fans were urging them to do and go all out to get Guardiola.
What remains to be seen now is to what extent the pair resume hostilities.
Guardiola left Barça drained by the strain of managing one of the most political clubs in football, but the at-times poisonous atmosphere that polluted the Clasicos had added to the sense that he was better out of it, so Mourinho had been a key contributory factor.
Their relationship will not be the same in England. Manchester City's rivalry with United cannot compare with Barcelona's with Real Madrid.
There are no political overtones and no matter how incendiary their rematch, there will be other battles to be fought.
Mourinho will not be able to make Guardiola his sole focus. After all it is with Arsene Wenger that he has the worst relationship. And he will also be taking on Antonio Conte at his former club and possibly Manuel Pellegrini at Everton.
The old enmity will not resurface with the same intensity. Neither will the even older friendship make a comeback.
Who knows they might even share a post-match glass of wine.
If they do Guardiola will probably still make sure Mourinho drinks from his cup first … just in case.
Jose Mourinho’s hitlist
Jose Mourinho’s impending arrival at Manchester United will place question marks over several of the club’s players. Here are the 10 players most at risk and their chances of survival?
JUAN MATA: The Spaniard perhaps has most to worry about from Mourinho’s appointment, having been sold to United by the Portuguese in 2014, but while Mata lacks the pace and physical strength to become a key man under Mourinho, his knack of big goals in may yet play in his favour. SURVIVAL RATING: 6/10
MARCOS ROJO: The Argentine defender has endured an injury-hit time at Old Trafford since arriving from Sporting Lisbon. While Rojo possesses the physical attributes of a typical Mourinho defender, his poor concentration ensures his days will be numbered. SURVIVAL RATING: 3/10
ANDER HERRERA: The £28.8m midfielder is under threat because he lacks a defined role and has struggled to make an impact during two seasons at United/ Does not do enough to influence games and could be offloaded this summer. SURVIVAL RATING: 4/10
DALEY BLIND: The Dutch defender became a key man under Louis van Gaal, impressing at centre-half last season having also played in midfield and at full-back. Blind may lose his centre-back position under Mourinho, but his versatility will earn him a stay of execution. SURVIVAL RATING: 8/10
MICHAEL CARRICK: The 34-year-old is out of contract this summer and still waiting t hear if he will be offered a new deal, but his experience and knowledge of the Premier League is likely to see Carrick handed a one-year deal by Mourinho. SURVIVAL RATING: 8/10
PHIL JONES: Once regarded as a future England centre-half, but Jones has endured an injury nightmare at Old Trafford. But Mourinho likes to build his teams around a core of domestic players and Jones may yet be given the chance to prove himself for that reason. SURVIVAL RATING: 6/10
BASTIAN SCHWEINSTEIGER: The Germany captain was a major disappointment last season having arrived to great fanfare from Bayern Munich. A Van Gaal loyalist, Schweinsteiger may find life too demanding under Mourinho and he appears an obvious candidate to be moved on. SURVIVAL RATING: 2/10
MAROUANE FELLAINI: Fellaini divides opinion at Old Trafford, with many regarding the Belgian as typifying the worst of Van Gaal’s reign, but he is effective and Mourinho is likely to regarded the former Everton midfielder as a useful Plan B, particularly with his physical presence. SURVIVAL RATING: 7/10
MEMPHIS DEPAY: Mourinho turned Arjen Robben into a star during his first spell at Chelsea and Depay arrived at United with a reputation as Holland’s successor to the Bayern Munich winger. He had a disastrous first season, though, and needs to improve his attitude to survive under Mourinho. SURVIVAL RATING: 5/10
ADNAN JANUZAJ: Januzaj became a forgotten man under Van Gaal, but United still believe the Belgian can become a world-class talent. He will be forced to accept Mourinho’s tough approach, but it worked for Joe Cole at Chelsea and Januzaj could yet salvage his United career under the Special One. SURVIVAL RATING: 6/10