Manchester City have been phenomenal on home turf this season, scoring 42 goals in the process of winning all 11 home games prior to Monday night. The loss of both Sergio Aguero and Fernandinho was undoubtedly a major blow, but it is Mourinho and his side who must be handed much credit for the result.
Much was made earlier in the season of the Portuguese manager's decision to remove Juan Mata from the Chelsea starting lineup, instead generally preferring Oscar, Willian and Eden Hazard as his attacking midfield trio.
On this occasion, meanwhile, Oscar was omitted in favour of Ramires taking on a more advanced role. However, the same principles that saw Mata made redundant at the club were the foundation of this success—defensive responsibility and speed in transitions.
Ramires, Willian and Hazard were where the game was won for Chelsea on this occasion, with their disciplined approach important in restricting City as an attacking threat while also offering an outlet going forward.
Defensive pairing of John Terry and Gary Cahill, along with the imposing Nemanja Matic in midfield, then ensured a clean sheet was kept at the back.
An Early Example
From the opening minutes of the game it became clear just how Mourinho planned to trouble City. With Manuel Pellegrini's side pushing their full-backs forward, Chelsea looked to exploit the space on the flanks.
With defensive midfielders Martin Demichelis and Yaya Toure failing to fill the gaps, largely due to the Ivorian's indifference to defensive work, the Blues' strategy enjoyed some success.
The following three pictures show a Chelsea counter-attack developing in the opening minutes of the game and the failings of the City midfield duo to accommodate for their attacking full-backs.
The move ultimately led to a corner, after a collision between Vincent Kompany and Nemanja Nastasic almost presented Chelsea with a golden chance. The lack of organisation, though, was caused by their opponent's speed in transition.
Just a few minutes later and we have another example of Chelsea almost scoring from a counter-attack.
On this occasion, Demichelis has done his job well in covering for the absent Zabaleta on the right as Willian motors forward on that side.
With Toure far from determined to recover his position, though, the result is that Eden Hazard is given plentiful room in front of the defence to pick a pass and should have played in Eto'o given the space created behind Kompany, who had been drawn to the ball.
What actually occurred, though, was that Hazard ran with the ball himself across the defence and created a scoring opportunity, only for the offside flag to be raised against Eto'o and Ramires. It was another golden opportunity for an early goal.
Chelsea Defensive Masterclass
While Chelsea were causing City all sorts of problems, what we saw at the other end was a demonstration of just how to defend against counter-attacks in a first half that flowed from end to end.
From the following three pictures we can see that Mourinho's side were set up very differently. Only one full-back ventured forward at a time, while both stayed deep in this instance, while both defensive midfielders were quick to recover.
As Zabaleta picks up the ball and looks to feed Toure to spring the attack, we can see that David Luiz looks to immediately pressure the Ivorian. Colleague Nemanja Matic, meanwhile, is already looking to drop back.
Toure gets past Luiz, while both Jesus Navas and Aleksandar Kolarov are making strong runs down the side for City. The Chelsea back four, though, is already well positioned to defend the attack. Matic, too, is making good ground to cover.
Eventually, the attack develops with Kolarov on the left, but Chelsea are well organised and Ivanovic closes his countryman down quickly to recover the ball. The positioning of Matic and Luiz, as well as the full-backs, is completely different to that of City at the other end.
City's attacks weren't all from transitions, though, with Chelsea allowing their rivals 65 percent of possession on the night.
However, what Squawka statistics show is that the Blues made only 31 tackles compared to City's 54 on the night. Rather than seek to win the ball back, they held their positions and waited until the right opportunity arose.
A big part of that was the role of Hazard, Willian and Ramires, all of whom were excellent at tracking back and watching runners from midfield. As the following picture demonstrates, their industry enabled Chelsea to keep their shape in the face of City's spells of possession.
As a consequence, City were able to complete very few passes in and around the Chelsea area, as the following diagram demonstrates.
The Ivanovic Goal: Toure and Navas Fall Asleep
Branislav Ivanovic's 32nd-minute goal proved to be the difference between the two sides and came as a direct result of a Chelsea counter and poor defensive awareness from City players.
The first picture shows that, initially, Manchester City had been well set up to deal with the developing attack. However, that quickly changes.
An intelligent run from Hazard to the right, where he gathers the ball, drags across the City defence toward the left-back position. Demichelis, meanwhile, has failed to notice Eto'o dropping off the shoulder of Zabaleta.
With Hazard looking to cross and Eto'o well-placed, the defence drops back with the Belgian's forward run as would be expected.
Demichelis remains unmoved, while neither Navas nor Toure have noticed the space that opens up for Willian and Ramires in the area.
The ball eventually finds Ramires, and he is quickly chased down by a now desperate Kompany, with the ball rebounding to Ivanovic.
While City cannot legislate for the quality of the finish from Chelsea's right-back, the errors that led to the opportunity could and should have been prevented. It's hard to imagine that, at the other end, City players would have been given quite the same freedom inside the penalty area.
Between them, Chelsea's defence made 65 clearances over the course of the match, with Matic, Terry and Cahill alone making more (35) than the entire City team (33).
While their tackle count, as noted above, was low, Chelsea's positioning and defensive shape allowed them to deal with City's attacks as they developed. It was a team effort that justified Mourinho's emphasis on hard-working forward players.
At the other end, City's forward players were nowhere to be seen as attacks developed, and all too often, both full-backs and defensive midfielders were missing also.
Such a system creates wonderful attacking football that will break down almost all opposition that visits the Etihad this season. However, Mourinho's Chelsea are the best defence in the league, and on this evidence, it is easy to see how.
All non-cited statistics via Squawka.com.