Manchester United crushed Manchester City 4-2 at Old Trafford and sparked a string on viral images on Twitter. Sergio Aguero opened the scoring for City  but Ashley Young, Marouane Fellaini, Juan Mata and Chris Smalling all struck before Aguero's second to all-but end the champions' Barclays Premier League title hopes. And the big win in the Manchester derby inspired Twitter users to produce a series of viral images which tended to pick fun at City's expense. David Moyes is labelled as a football genius for signing goalscorers Juan Mata and Marouane Fellaini . A screenshot from the Austin Powers films pokes fun at Manchester City's sudden loss in form . Fellaini has been transformed from a joke figure to a key player during this season at Old Trafford . A City fan watching the game is shown wearing a United shirt after the score changes from 0-1 to 4-1 . The idea of City fans changing allegiances was popular. Here they are looking at buying a Chelsea shirt . There is now a clear gap between Untied and City in the Barclays Premier League - in the red side's favour . Chris Smalling scored his fourth league goal of the season which matches expensive loanee Radamel Falcao . 'Manchester is red!' - it's clear who the big winners were in the Manchester derby from this image .
Manchester United beat Manchester City 4-2 at Old Trafford on Sunday .
Ashley Young, Marouane Fellaini, Juan Mata and Chris Smalling all scored .
Internet pranksters ripped into the Barclays Premier League champions .