#1 Manchester United 1-6 Manchester City (23 October 2011)
Not many teams can boast humiliating their fierce rivals with a 6-1 win as visitors, but Manchester City can.
As for Manchester United, the disgrace and the lacerations that they suffered are downright indelible. What's more, Wayne Rooney couldn't have asked for a more worse birthday, as he turned 26 immediately the next day following the nerve-wrenching fixture.
Roberto Mancini's men dominated the game like never before, and it was always going to be a tough task for United to grind out a positive result. However, few could have predicted such a massive win for the Citizens.
Mario Balotelli opened the scoring for City and the scoreboard stayed 1-0 until the hour mark when he struck again.
The goal was just the beginning of the worst 30 minutes Manchester United have ever played in their history. Johnny Evans' red card at the beginning of the second half proved to be the turning point of the game for Manchester City.
Sergio Aguero added a third on the 69th minute, followed by a Darren Fletcher goal that kept the hopes of a comeback alive.
Manchester City inflicted unbearable pain on their rivals by scoring three goals in four minutes in the 90th minute and stoppage time, courtesy to a goal by David Silva and a brace by substitute Edin Dzeko.
Manchester United suffered their worst home defeat since 1955, while the emphatic win remained a cherry on the cake for the Premier League title that City clinched in a memorable fashion in season 2011-12.