The United and City chiefs have met 16 times previously with the bragging rights between the rivals as big as ever for this weekend's derby.
It's a rivalry that encapsulated the best of and worst of modern football and Jose Mourinho and Pep Guardiola are ready to lock horns once again.
The elite managers face off for the 17th time in their careers as Manchester United welcome Manchester City to Old Trafford on Saturday.
It is the first official meeting between the pair since Mourinho's Chelsea played Guardiola's Bayern Munich in the 2013 UEFA Super Cup.
The Spaniard has the edge over his Portuguese foe with eight victories - including the penalty shoot-out triumph with Bayern against Chelsea - while the Special One has managed just three wins with five ending in a draw.
"Your statistics are wrong and very wrong," Mourinho famously claimed after being told of his head-to-head record. "Go there and see what happened with Inter in the Champions League semi-final.
"I won the Spanish cup final in Valencia, I won the Super Cup in Spain. I was champion in Spain. I won the match for the title in Barcelona with Real Madrid."
Inter Milan 0-0 Barcelona
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                    Inter Milan's Cristian Chivu (L) fights for the ball with Barcelona's Lionel Messi
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Champions League group stage at San Siro (16/09/2009)
The beginning of the fierce rivalry ended goalless in Group F of the Champions League group stage as Zlatan Ibrahimovic returned to the San Siro after his blockbuster transfer to the Camp Nou that summer.
The reigning European champions dominated the contest with the mercurial Swedish striker fluffing the best chance after cushioning Dani Alves' cross to volley wide.
Barcelona 2-0 Inter Milan
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                    Barcelona's Gerard Pique celebrates after scoring against Inter Milan
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                    Barcelona's Pedro Rodriguez netted the second at the Nou Camp
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Champions League group stage at Camp Nou (24/11/2009)
Barcelona continued their supremacy from the first group stage meeting but this time managed to make their dominance count as Gerard Pique and Pedro Rodriguez struck.
It was vintage Xavi, who put on a clinic to inspire Pep's men and ensure Thiago Motta and Esteban Cambiasso chased shadows all evening.
Inter Milan 3-1 Barcelona
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                    Inter Milan's Argentinian forward Diego Milito scores the crucial goal to kill Barca
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Champions League semi-final first leg at San Siro (20/04/2010)
One of the defining moments in Mourinho's career: Pedro silenced a deafening San Siro crowd early on but the Nerazzurri rallied with a series of devastating counter-attacks to dent Pep's hopes of becoming the first side to retain the Champions League.
The brilliant attacking trident of Diego Milito, Samuel Eto'o and Wesley Sneijder combined with the Dutch playmaker equalising before the buccaneering Maicon gave Mourinho's side the lead.
Perhaps rather uncharacteristically, Mourinho went for the kill with Milito's header ensuring a crucial two-goal lead after the first leg.
Barcelona 1-0 Inter Milan (agg. 2-3)
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                   Mourinho sprinted on to the Camp Nou pitch at full-time in celebration
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Champions League semi-final second leg at Camp Nou (28/04/2010)
If the first leg was untypical of Mourinho sides over the years, the second leg reverted to the Portuguese's bread and butter in an enthralling climax to a legendary tie.
Led by the indomitable Lucio and Walter Samuel at the back, Mourinho's troops overcame the injustice of Motta's red card following Sergio Busquets' theatrics to reach their first final since 1972.
Pique's 84th minute strike set up a grandstand finish and the fervent Camp Nou crowd thought they'd won the tie when Bojan smashed home, only for the referee to rule it out for a controversial hand ball from Yaya Toure in the build-up.
Barcelona 5-0 Real Madrid
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                   Emotions spill over as Mourinho suffers his heaviest defeat as a manager
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La Liga at Camp Nou (29/11/2010)
Surely the greatest of humiliations in Mourinho's career: a rampant Barcelona hit five past Madrid in the Portuguese's first Clasico after his all-time greatest start to life at the helm in Madrid.
A signature game for Lionel Messi's period deployed as a false nine, Mourinho had no answer to the Argentinian magician dropping deep and opening up space for both himself and Xavi to slice Madrid apart.
David Villa was notably at his scintillating best and his two goals - both found by Messi's exquisite passes - were the highlights as Guardiola handed Mourinho his heaviest defeat as a manager.
Real Madrid 1-1 Barcelona
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                   Lionel Messi nets from the spot to take a point from the Bernabeu
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La Liga at Santiago Bernabeu (16/04/2011)
The first of four games between the sides in little over two weeks was a gentle appetiser with Barcelona eight points clear and all but secure of winning the title.
Messi and Cristiano Ronaldo exchanged penalties in the second half with the teams unable to be split.
Barcelona 0-1 Real Madrid

                   Mourinho is tossed into the air as Madrid wildly celebrate their triumph
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Copa del Rey final at Mestalla (20/04/2011)
This was Mourinho's first dagger to Guardiola as Real Madrid boss at the cup final in Valencia to secure silverware in his debut season at the Bernabeu.
Cristiano Ronaldo's towering header to convert Angel Di Maria's sublime cross in extra-time won the trophy.
Real Madrid 0-2 Barcelona
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Champions League semi-final first leg at Santiago Bernabeu (27/04/2011)
Another for the greatest Messi moments scrap book as the Barcelona No.10 struck late twice to punish 10-man Madrid and all but secure their place at Wembley.
The first was converted from close range after good work from Ibrahim Afellay down the right but his second was something a little bit special.
Picking the ball up near the half-way line, Messi exchanged passes with Busquets before a mazy dribble and scooped finish past Iker Casillas brought wild scenes of Barcelona celebrations.
Barcelona 1-1 Real Madrid (Agg. 3-1)
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                   Busquets takes out Ronaldo during the Champions League second leg
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Champions League semi-final second leg at Camp Nou (03/05/2011)
Madrid mustered some semblance of a comeback in a spirited display in the second leg but Pedro's opener dashed any hopes of a turnaround.
Marcelo equalised to keep the aggregate score respectable but Guardiola's side advanced, where they would swat Manchester United aside with ease at the home of English football to win their fourth European crown.
Real Madrid 2-2 Barcelona
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                   Mourinho embraces Guardiola in the Bernabeu dugout
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Spanish Super Cup first leg at Santiago Bernabeu (14/08/2011)
A pulsating contest that saw Villa and Messi give the visitors a half-time lead after Mesut Ozil's opener.
Xabi Alonso equalised in the second half with the second leg beautifully poised.
Barcelona 3-2 Real Madrid
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                   Mourinho gouges Tito Vilanova's eye as a brawl breaks out to end the Clasico
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Spanish Super Cup second leg at Camp Nou (17/08/2011)
This was one of the most bitter yet thrilling encounters between Mourinho and Guardiola which saw Karim Benzema level the tie at four apiece with eight minutes to go.
Messi's sweetly struck volley in the 88th minute decided the Super Cup before all hell broke loose in stoppage time.
Marcelo's horror challenge on Cesc Fabregas led to the Brazilian, Mesut Ozil and David Villa all being sent off after a brawl and Mourinho poking his finger in the late Tito Vilanova's eye.
Real Madrid 1-3 Barcelona
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                   Guardiola confers with Andres Iniesta as the Blaugrana secure victory at the Bernabeu
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La Liga at Santiago Bernabeu (10/12/2011)
Barcelona triumphed once again at their eternal rival's home despite Karim Benzema putting Madrid in front with the fastest goal in El Clasico history after 23 seconds.
Pep's men typically rallied back with Alexis Sanchez, Xavi and Cesc Fabregas' first Clasico goal enough to bring the points back to Catalonia.
Real Madrid 1-2 Barcelona

                   Ronaldo puts the hosts in front at the Bernabeu
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Copa del Rey quarter-final first leg at Santiago Bernabeu (18/01/2012)
Despite Pinto's suspect goalkeeping allowing Ronaldo's drive to squeeze through his legs from a narrow angle, Barcelona took a first-leg lead.
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.
Barcelona 2-2 Real Madrid (Agg. 4-3)

                   Mourinho delivers a message to Sergio Ramos in a bid to overturn the first leg deficit
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Copa del Rey quarter-final second leg at Camp Nou (25/01/2012)
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.
Barcelona 1-2 Real Madrid
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                       Jose Mourinho and Josep Guardiola gesture during El clasico
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                   Sami Khedira puts the visitors in front
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La Liga at Camp Nou (21/04/2012)
After a miserable run against his rival, Mourinho landed the final blow before his time at the Bernabeu came to a bitter end.
Sanchez equalised Sami Khedira's effort with one of the scrappiest goals ever seen in El Clasico before Cristiano rounded the goalkeeper and finished to earn the win for Mourinho and infuriate thousands of Catalans by gesturing for them to calm down.
Bayern Munich 2-2 Chelsea
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                   Guardiola was especially animated after Ribery levelled for Bayern
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UEFA Super Cup at Eden Arena (30/08/2013)
A trophy seldom cared for by the elite managers, but there was evidently some needle here and desperation from Mourinho's end to get one over Pep and deliver a European trophy for the Blues upon returning to the club.
Fernando Torres' rasping volley was cancelled out by Franck Ribery's low drive before Eden Hazard's solo effort looked to have won it for Mourinho. But the Blues switched off late to allow Javier Martinez to equalise in stoppage time at the end of extra-time.
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After nine perfect penalties in the shoot-out, Manuel Neuer dived low to his left to keep out Romelu Lukaku's spot kick and hand Guardiola the trophy.