It's a managerial rivalry that's encapsulated the very best and worst of the modern game.
A frequent duel between the two of the sport's brightest minds, Pep Guardiola vs Jose Mourinho is a sideline bout like no other.
It's a rivalry that's spanned three countries, decided however many pieces of silverware and sparked some of the most intriguing tactical innovations. The fact the two masterminds are considered to be on opposing ends of the philosophical spectrum makes their clashes all the more enthralling.
Revolutionary Italian coach Arrigo Sacchi described it as "like having two Picasso's in the same period" which depicts the rivalry perfectly.
Fancy a trip down memory lane to revisit every game they've ever contested? Yeah, we do too - let's dig in!
1. Inter 0-0 Barcelona (16/09/09)
A historic rivalry endured a rather tame opening.
On Zlatan Ibrahimovic's return to San Siro, neither side were able to find the breakthrough in this Champions League group stage clash.
2. Barcelona 2-0 Inter (24/09/09)
The return fixture saw Barcelona's supremacy laid bare.
Buoyed by Xavi's midfield magic, La Blaugrana secured a 2-0 victory via goals from Gerard Pique and Pedro which helped them top the group.
The contest served as a mere teaser to what would ensue months later.
3. Inter 3-1 Barcelona (20/04/10)
In one of the most notorious Champions League ties in history, Inter's counter-attacking brilliance overwhelmed Guardiola's men at San Siro.
Goals from Wesley Sneijder, Maicon and Diego Milito ensured that Pedro's early opener was long forgotten.
4. Barcelona 1-0 Inter (28/04/10)
The greatest execution of parking the bus ever. Period.
Masterminded by their determined manager and spearheaded by the indomitable centre-back pairing of Lucio and Walter Samuel, Inter overcame the injustice of Thiago Motta's red card to progress into the final despite a late Pique strike.
Mourinho had his revenge.
5. Barcelona 5-0 Real Madrid (29/11/10)
The greatest humiliation of Mourinho's career arrived in his maiden Clasico.
Once again, it was Xavi who ran the show with Mourinho's decision to man-mark the Spaniard with languid playmaker Mesut Ozil one of his great tactical failings.
Real's high line was constantly exposed as Lionel Messi wreaked havoc from a false nine position in the 5-0 rout.
6. Real Madrid 1-1 Barcelona (16/04/11)
This fixture was merely the first of four Clasico's in an unprecedented 18-day window. A tactically supreme series that would essentially decide three major trophies.
The spoils were shared in the opening bout, as Messi and Cristiano Ronaldo bagged penalties.
Mourinho's utilisation of Pepe in midfield was a sign of things to come, resembling Real's Clasico style.
7. Barcelona 0-1 Real Madrid (20/04/11)
Mourinho's smart utilisation of Ronaldo as an outright centre forward paid dividends as the Portuguese superstar headed home in extra time to hand Real the Copa del Rey.
Pepe, meanwhile, was immense in a box-to-box role.
8. Real Madrid 0-2 Barcelona (27/04/11)
Hostilities between the two managers were at an all-time high heading into this one, with Guardiola labelling Mourinho the "f***ing chief" of Real's press room in a pre-match rant.
The typically unfazed Catalan had been rattled, but victory in the first leg of the Champions League semi-final ensured his on-pitch dominance was maintained.
A Messi brace following Pepe's dismissal separated the pair in a stop-start war of attrition
9. Barcelona 1-1 Real Madrid (03/05/11)
An uneventful contest as Marcelo cancelled out Pedro's opener with the tie all but decided from the first leg.
Barcelona advanced and dazzled their way to further European glory.
10. Real Madrid 2-2 Barcelona (14/08/11)
Real dominated the first leg of the Spanish Super Cup which kickstarted a dramatic 2011/12 campaign.
Barcelona were saved by sequences of magic from Messi and David Villa to leave the Bernabeu with a 2-2 draw.
11. Barcelona 3-2 Real Madrid (17/08/11)
While Messi was fairly quiet during the four-game sequence in 2010/11 -barring a tie-clinching 15-minute spell - the second leg of the domestic Super Cup was unquestionably the Messi show.
The Argentine scored twice and set-up the other in a 3-2 Barca triumph (5-4 aggregate) as the unsavoury scenes - including Mourinho's eye gouge on Tito Vilanova - marred an otherwise terrific contest.
12. Real Madrid 1-3 Barcelona (10/12/11)
This bout saw one of Guardiola's most complex tactical plans with Barcelona deploying an almost indecipherable system at the Bernabeu.
Karim Benzema handed the hosts the lead within 30 seconds before Pep's system switch after ten minutes gave the visitors total control in an impressive 3-1 triumph.
13. Real Madrid 1-2 Barcelona (18/01/12)
Despite Jose Pinto's suspect goalkeeping allowing Ronaldo's drive to squeeze through his legs from a narrow-angle, Barcelona took a first-leg lead in this Copa del Rey quarter-final tie.
Barça stalwart Carles Puyol powered home a header to equalise before a collectors' item in the shape of Eric Abidal's neat finish secured the win.
14. Barcelona 2-2 Real Madrid (25/01/12)
The tie was effectively ended when Messi's explosive run from the half-way line to the edge of the penalty area before slipping in Pedro to drive home the opener.
Dani Alves sent a rocket into the top left corner to double the lead before Pep's side took their pedal off the gas to allow Ronaldo and Benzema to put some respectability on the aggregate score.
15. Barcelona 1-2 Real Madrid (21/04/12)
With Real heading into Catalonia four points clear of their Clasico rivals in La Liga, this was a title showdown.
However, with Barca finally starting to unravel under Pep and Los Blancos emerging as a counter-attacking juggernaut in 11/12, the visitors claimed a memorable victory.
Sami Khedira scrambled home from a set-piece before Real secured the imperative three points via Ronaldo rounding off a trademark transition.
Guardiola would later announce his exit from Catalonia at the end of the season.
16. Bayern Munich 2-2 Chelsea (30/08/13)
Ah finally, a change of scenery.
Following a year's sabbatical after his Barcelona exit, Guardiola signed a three-year deal with Bayern as Mourinho returned to Chelsea that summer also.
However, the two met early into their reigns at their respective new clubs in the 2013 European Super Cup. In a contest where Phillip Lahm was used as the pivot for they very first time, an injury-riddled Bayern forced the game to penalties after a last-gasp Javi Martinez equaliser in extra time.
A Romelu Lukaku miss in the shootout handed the Spaniard his first piece of silverware in Bavaria.
17. Manchester United 1-2 Manchester City (10/09/16)
The first Manchester derby between the pair saw an impressive City race into a 2-0 lead thanks to goals from Kevin De Bruyne and Kelechi Iheanacho.
A Claudio Bravo error handed the hosts a lifeline before the break but the visitors held on for victory.
18. Manchester United 1-0 Manchester City (26/09/16)
Humiliated 4-0 by Antonio Conte's Chelsea the week prior, Mourinho was in desperate need of a result in this EFL Cup fourth-round tie.
And thanks to a Juan Mata strike, it's one he got with United going on to win the competition.
19. Manchester City 0-0 Manchester United (27/04/17)
Perhaps the most forgettable of the lot.
City were dominant but failed to test an imperious David de Gea between the sticks.
A Marouane Fellaini red card for a despicable headbutt on Sergio Aguero was certainly the highlight of a drab contest.
20. Manchester United 1-2 Manchester City (10/12/17)
City were seemingly all but champions following this December triumph, that's how dominant their 2017/18 side was.
Although Marcus Rashford cancelled out David Silva's opener, a Nicolas Otamendi strike handed the visitors the initiative after the break. One they refused to relinquish thanks to some late Ederson heroics.
21. Manchester City 2-3 Manchester United (07/04/18)
Mourinho looked on course for another Guardiola-induced humiliation as the imperious Cityzens flew into a brisk 2-0 lead looking to wrap up the title.
However, seemingly emboldened by the Special One's wise half-time words, United emerged after the restart like a unit possessed. Three goals in 16 second-half minutes swiftly turned City's title celebration into a funeral as Paul Pogba netted twice.
22. Manchester City 3-1 Manchester United (11/11/18)
This was just another jolt in Mourinho's Manchester demise.
The Red Devils were worryingly second best as a late Ilkay Gundogan strike confirmed a 3-1 victory for Guardiola's eventual champions.
Mourinho was sacked less than a month later.
23. Tottenham 2-0 Manchester City (02/02/20)
This was the most typical of Mourinho victories.
After an hour of City supremacy, Oleksandr Zinchenko's dismissal served as the ultimate turning point.
A previously suffocated Spurs, buoyed by their man advantage, scored twice in the second period - including a superb debut goal from Steven Bergwijn - to grab all three points.