Manchester United's Wayne Rooney watches during their English Premier League soccer match against Manchester City at the Etihad stadium in Manchester, northern England April 30, 2012. [Photo/Agencies]
Kompany was enjoying a good old-fashioned scrap with Wayne Rooney and the City captain was booked for one rumbustious tackle on the England striker who became marginalised as the half wore on.
United found themselves pinned back as City began to hog possession and Aguero again failed to make the most of another half chance that came his way.
The visitors would have been happy to hear the halftime whistle on level terms but Kompany, sent off when the sides met in the FA Cup this season, chose the perfect time to score.
When Silva sent in a corner the Belgian evaded the attentions of marker Chris Smalling and thumped a powerful header past the helpless David de Gea.
United could never really find any attacking rhythm after the break as City erected a sky blue wall to deny the visiting forwards any quality service.
With the clock ticking down and United becoming desperate, tempers flared in the technical area with Mancini and Ferguson involved in a heated exchange.
City's Yaya Toure almost gave his side breathing space with a shot that whistled wide.
Ferguson then threw on Danny Welbeck and Ashley Young to bolster United's attack but City held firm to spark a deafening rendition of the club anthem Blue Moon.