Arsenal dominated the early exchanges but the visitors slowly emerged from their shell, defending strongly. With David Silva out from the beginning and Yaya Touré soon following him to the sidelines – replaced by the ineffective David Pizarro – City were left without perhaps their two most influential players this season. Samir Nasri seemed most likely to shine in their place and started to search out the space between and behind Laurent Koscielny and Thomas Vermaelen as the first half wore on.

In the second period City emerged with more ambition: Mancini moved Gareth Barry further forward and Pablo Zabaleta had a burst of energy. But Arsenal parried and pushed City on to the back foot. In attack Sergio Agüero and Mario Balotelli looked distant and, without Silva sliding passes through, they never troubled Wojciech Szczesny. But it was in midfield that their troubles began.

A feature of Arsenal's improvement has been the combination play of the three midfield men and here Alex Song, the most powerful of midfield bases, led the charge.

Arsenal’s midfield movement opened up space for Alex Song’s surges and helped them to dominate the important middle third at the Emirates. Photograph: Graphic

The understanding and movement of Arsenal's midfield trio is a joy to watch and a masterclass in coaching. They are always on the move: one makes a forward run, one peels off at an angle and between them they make the space for the deepest man to move forward with the ball (see diagram). This continual movement off the ball gives the opponents marking problems.

When Song drives forward he invariably seeks his side's goalscorer, Robin van Persie, curving lofted passes into his path. There was a time when he was considered purely a "Makelele type", sitting in front of his centre-backs, cutting out danger. He began his career at Arsenal as a centre-back, where few staff members considered him first-team material. Arsène Wenger had faith and he is seeing the fruits of his outstanding judgment.

Without Silva's guile and Yaya's surge, City were submerged – they had only five attempts at goal. Balotelli was a catalyst only for disaster, a player who does not deserve colleagues of the stature of Vincent Kompany and Joleon Lescott, both giants once more for the fading light blues.

Song, one of the Premier League's most underrated players, hit all the right notes while his team-mates have proved conclusively to City that money cannot buy you love. There is a feeling about Arsenal that translates into tenacious harmony.