Deconstructing Manchester United's 4-2 win over Manchester City

Manchester United turned in another excellent performance to see off rivals City 4-2 at Old Trafford on Sunday. After a dodgy opening few minutes, the Reds steadied the ship and roared back to record a victory that seems to all but guarantee Champions League football. So, how did United's first derby win in three years come about? Let's take a look at the game's key tactical pointers.

Lineups

Louis van Gaal made only one change to the team that beat Aston Villa last weekend, with Marcos Rojo dropped to make way for a returning Chris Smalling. Manchester City, meanwhile, started with Martín Demichelis instead of Eliaquim Mangala, while James Milner was given the nod over Edin Džeko. The upshot was that City set up to match United's 4-2-3-1, instead of playing with a second striker alongside Sergio Agüero.

City's bright start

There's no doubt that there is substance to the old adage that goals change games, and as a result, United could've been in real trouble after going behind so early.

Fittingly, City's eighth minute opener came through a tidy combination of the three players that United struggled with early on. James Milner -- nominally City's attacking midfielder, presumably in order to try and hassle Michael Carrick when United were in possession -- drifted out to the left flank, affording David Silva the room to burst through into the box unmarked. A smart reverse pass found the Spaniard, whose low cross was tapped home by Sergio Agüero.

The criss-crossing between Silva and Milner was presumably a routine that City worked on in training, as it was a common feature of the opening exchanges. United's defence struggled to deal with such fluidity, and matters were complicated yet further by Agüero drifting laterally across the pitch, often dragging either Phil Jones or Chris Smalling with him. Holes duly appeared through United's defence, and the game could have been over before it had really begun.

Out of possession, City were almost as impressive. Milner stuck to Carrick like glue, Agüero was typically irritating in his pressing from the front, and the team were very cohesive in shifting across the field. The result was that United often were squeezed into the wide areas, where the lack of passing lanes resulted in rapid turnovers of possession. Things really didn't look good.

Juan Mata

Juan Mata was especially anonymous in the difficult early moments, though a crucial switch from the Spaniard midway through the first half may well have completely changed the momentum of the game. Having struggled against the pressing of Gaël Clichy, who was doing an effective man marking job, Mata moved much narrower, often into a central midfield position. Suddenly, Clichy had no one to mark, and United had a spare player in the centre of the field.

Mata was able to link play effectively, and buy more space for his midfield counterparts, Ander Herrera and Michael Carrick. Tellingly, the Spaniard played a big role in United's second goal, when he played a stunning pass out to Ashley Young, who delivered a tremendous cross for Marouane Fellaini to head home at the far post. Mata also took it upon himself to mark David Silva, who was fairly quiet after his early assist.

Of course, the risk of Mata playing so narrowly was that City left-back Gaël Clichy would be able to wreak havoc by advancing down the flank unopposed. However, Ander Herrera negated this threat effectively, pushing out to close down as was required.

United off the ball

The first few minutes were deeply perturbing from a defensive perspective, with City's interchanging front four contorting United's defence out of postion. Phil Jones and Chris Smalling looked completely out of their depth, and the mobility of Agüero meant any plans to try and mark the Argentine out of the game went out of the window. Leaving out United's best centre-back, Marcos Rojo, looked a potentially costly decision.

However, by the end of the game, both of the centre-backs had recovered excellently. They certainly weren't perfect performances, but they mostly did what was required, successfully dealing with one of the most intelligent strikers in the league with intelligent zonal play. Phil Jones even managed to look competent on the ball, carrying it forward and regularly distributing wide. It remains to be seen whether this is still United's best defensive pairing -- Rojo's pace and mobility means I'd be tempted to stick with him -- but things worked out well in this game.

United were largely effective off the ball throughout the remainder of the match, and good pressure meant that City recorded what was quite comfortably their lowest pass completion rate of the season so far. An honourable mention should go to Antonio Valencia, who made a couple of brilliant defensive interventions to bail Smalling and Jones out. Has there ever been a winger-turned-full-back as good at defending and as poor at attacking as the Ecuadorian?

Manchester United's left

When Jesús Navas steamed past Daley Blind to chase down a Martín Demichelis through ball in the first few minutes, fearing for the Dutchman against one of the Premier League's most direct wingers was understandable. However, he recovered to put in a very tidy performance, of which supporting the excellent Young was arguably the most important aspect.

Young, who scored a goal and had a hand in two others, was rightly given the man of the match prize after an excellent performance. His crossing ability caused City's defence massive problems, while his positioning high on the left flank presumably had the useful side-effect of keeping City right-back Pablo Zabaleta pinned back inside his own half.

Marouane Fellaini

Marouane Fellaini is having an excellent season, but this may have been his best performance yet. The Belgian was utterly devastating, with City completely unable to keep him quiet. Throughout the game, he often stayed high up the field, almost playing as a second striker. His aerial strength meant that he was able to bring down almost everything United thumped in his direction, and he arrived perfectly at the back post to nod Young's cross beyond Joe Hart.

At the start of the game, the responsibility for keeping him quiet seemed to have been delegated to midfielder Yaya Touré. However, the Ivorian proved himself to be utterly incapable of doing the requisite defensive work, and City payed a heavy price. In the build-up to United's third goal, Touré's laziness meant Demichelis charged out of defence to try and close Fellaini down. However, that left a gaping hole for Juan Mata to skip into. A brilliant Wayne Rooney pass later, and the Spaniard was clean through on Hart's goal, poised to give United a two-goal lead.

Fellaini will never be a world class technician, but he is a gigantic pain in the backside. He offers great variety in United's tactical options, and even against great teams, simple is sometimes best. Just as van Gaal suggested a few weeks back, he was invaluable in beating City's first press through a route-one pass -- and once you're past that, Manuel Pellegrini's side are really very vulnerable.