As Pep Guardiola and Jose Mourinho finally meet again, for the first time in over three years, what matches must their first Manchester derby live up to?
What games stand out as statement encounters?
Miguel Delaney has the tale of the tape:
1. Mourinho's finest moment
Inter Milan 3-1 Barcelona, Champions League semifinal first leg, April 20, 2010
The 2009-10 treble at Inter was arguably the Portuguese's greatest feat, and the win over Barca that campaign's peak, but the man himself would go even further. Of that 3-1 victory at the San Siro, Mourinho has said: "Inter played the best game of the last 50 years."
It certainly brought together the best of Mourinho's management, as the Italian champions combined assured defending with ruthlessly cutting counter-attack, thanks to forensic tactical planning and fierce motivation.
Having gone behind to a Pedro away goal on 19 minutes, Inter displayed supreme resilience to respond with a Wesley Sneijder strike, before they proceeded to lure Barca into trap after trap, with Maicon and Diego Milito making it 3-1.
"We played in the first game and won 3-1, but it should have been four or five," Mourinho later said. "We went with everything we had."
It showcased everything that has made Mourinho's career, in what was a signature performance.
2. Guardiola's finest moment
Barcelona 5-0 Real Madrid, La Liga, Nov. 29, 2010
This was not just revenge for Inter, nor even the sweetest of Clasico wins. It went far beyond all that, and transcended the season, as the most complete expression of the football philosophy that Guardiola had come to represent. Total football, total dominance.
As Xavi enthused in Sid Lowe's "Fear and Loathing in La Liga," Real "didn't even touch the ball. It was fantastic."
Xavi himself hit the first, with Pedro making it 2-0 before Leo Messi divinely set up two for David Villa. Jeffren hit the final goal on 90 minutes, to make the scoreline a symbolic 5-0.
Afterwards, the Barca players gave themselves a standing ovation in the dressing room a minute long, while Real president Florentino Perez described it as his worst-ever result. It may well have been Guardiola's best ever moment, and it is probably fitting he had the biggest win in the rivalry, reflecting his vastly superior record of seven wins to three.
3. Most epic game
Barcelona 1-0 Inter Milan, Champions League semifinal second leg, April, 28 2010
It might have been one of the lowest scoring meetings, but very few of the other 15 -- or indeed any match full-stop -- could have matched this exhaustingly exhilarating encounter for high stakes, high intensity and high drama.
If the first leg was the ultimate showcase of Mourinho's management, this was the ultimate clash of styles: All-out defence against all-out attack, as Barca desperately chased two goals, and Inter defiantly protected their lead.
That pushed both teams, the players, and the game to the very limit. Sergio Busquets' play-acting got Thiago Motta sent off, forcing Inter to withdraw and willingly invite wave after wave of Barca attack.
With the tension ratcheting up, Gerard Pique scored a fine goal, before glorious chaos ensued. Bojan Krkic thought he'd scored the decisive goal, only for the flag to go up. For all the bad blood that was to come, this was such an impressively full-blooded encounter.
4. When the rivalry was at its most intense
Real Madrid 0-2 Barcelona, Champions League semifinal first leg, April 27, 2011
As with so much in this rivalry, their most intense matches were not just outstanding for the two managers or the clubs, but outstanding for football history.
There has rarely been a series of games like the four Real-Barcelona matches to decide everything between 16 April and 3 May 2011.
It all escalated, in so many senses. They first met in the league at the Bernabeu, as Barca effectively wrapped up the Spanish title with a 1-1 draw, before Real hit back with a 1-0 extra-time victory in the Copa del Rey final ahead of the main event: The Champions League semi-final.
Amidst all of that, it was little wonder the first leg was such a suffocated match, or that there was almost as much drama off the pitch. Guardiola set a tone by fronting up to Mourinho for once in a press conference, although that only saw the teams entrench themselves during the game, as Real sat deep and Barca's passing became so prosaic.
The game was finally enlivened by Messi's individual brilliance, but that after a Pepe red card that saw Mourinho controversially hint at conspiracies after the game. Afterwards, Guardiola was heard to express his gratitude that it was finally over. It was that demanding.
5. Most controversial
Barcelona 3-2 Real Madrid, Spanish Super Cup second leg, Aug. 17 2011
One ugly moment sticks out so much that it's easy to forget this match featured three red cards, nine yellows and Messi hitting the last of five goals with a brilliant late winner.
That's how bad Mourinho poking his finger in the late Tito Vilanova's eye was, that's how acrimonious the rivalry had become.
6. Dullest game
Inter Milan 0-0 Barcelona, Champions League group stage, Sept. 16 2009
Proof that there aren't always fireworks or fine drama, although it is probably relevant that this was their first-ever competitive meeting.
In fact, it's remarkable to consider that such a rancorous rivalry began in so subdued a manner. It ended up being the ultimate phoney war, as both sides just felt each other out.
There was barely anything of note, other than Zlatan Ibrahimovic missing an eighth-minute half-chance, and the torrid reception the Swede surprisingly got for leaving Inter that summer. Given the circumstances right now, with both managers in new jobs, we may actually see something similar this weekend at Old Trafford.