The visitors came away battled, bloodied and bruised, but they also walked away with a three-point haul—the first team to do so in the league for almost two years.
Let's take a closer look at the tactical duel between the managers.
Starting XIs and Formations
Roberto Mancini chose a fairly standard 4-2-3-1 for his team, with Mario Balotelli atop the formation.
Sergio Aguero started the match "in the hole" behind the Italian, wedged between false wingers Samir Nasri and David Silva.
Sir Alex Ferguson opted for a 4-4-2 built to counterattack, reinstating wideman Antonio Valencia on the right and keeping Rafael in after being hauled off early at the Madejski Stadium last week.
Channels and Movement
Just like the last three encounters, United surrendered possession of the ball early on and took to the disrupting method.
High pressing as a team, organised movement and some last-ditch tackles made it very difficult for City to use the ball efficiently despite seeing plenty of it. When United went 1-0 up after only enjoying around 30-percent possession, it seemed the match would be a classic counterattacking masterpiece.
United's first goal took just 15 seconds from the first touch to the last. With City piling forward, the hosts were left continually short at the back against Robin van Persie and Wayne Rooney's clever movement.
The two strikers were able to exploit the channels and drag defenders wide of their natural positions, creating space moving forward for other players to drop into and use. The wide men were able to stretch the pitch and open pockets for the midfielders to exploits.
Mancini didn't make his usual move to the 3-5-2 system, instead throwing Edin Dzeko on up front in what was no longer a structured formation.
Clear-cut opportunities started to appear, and before you knew it, it was 2-2. By no means was this a product of any genius tactical innovation, though, it was simply wear and tear combined with the absence of Jonny Evans, who was immense until he was taken off.
Ferguson, too, stuck to his method. A point at the Etihad Stadium, where no team had won in the league for two years, is by no means a bad result when you're three points clear at the top.
But Van Persie showed everyone why he's worth his big price tag, curling in a beautiful free kick at the death to win it.
One typically stubborn manager against one flexible tactician is always a good watch, but the latter disappointed today.
He wasn't his usual bold self, seemed reluctant to make the fearless changes we've become accustomed to and ultimately failed to win a game his team probably shaded.
But props to Ferguson—he sacrificed possession, used two strikers and played to his team's strengths. A win for the red half, a win for Fergie.