Cape Town - Manchester United defender Rio Ferdinand has made light of the situation after being struck by a coin during United's derby win over rivals Manchester City on Sunday.The English centre-back was left with blood pouring from his face after being hit by a missile apparently thrown from the crowd in the aftermath of Robin van Persie's injury-time winner for United at the Etihad Stadium. VIDEO: Rio Ferdinand struck by coinFerdinand wrote on Twitter: what a result,3points! Sweet! Whoever threw that coin,what a shot! Can't believe it was a copper 2p....could have at least been a £1 coin! Soon thereafter, Ferdinand, in a more serious tone, wrote: Respect to Joe Hart for protecting that idiot who ran on!! Love the banter between fans but there is a point when it goes too far...calm it! Manchester City were quick to apologise for the incident and an investigation has been launched.