Man City left Sir Alex Ferguson furious after Yaya Toure helped deliver "slap in the face"

For Yaya Toure, the brutal “slap in the face” Manchester City gave their local rivals marked a power shift in English football.

City's 6-1 mauling of Manchester United at Old Trafford in October 2011, en route to winning their first Premier League title, proved the turning point for the Blues. Since then, City have become the dominant football force in Manchester and in English football, with six titles in 12 years, including five of the last six.

Although City had beaten United 1-0 at Wembley in the FA Cup semi-finals six months earlier, Toure believes the emphatic Old Trafford win proved they had become a major force.