Video: Iker Casillas’ awful howler in Madrid derby sets Atletico on their way to a 4-0 rout

Bad news Manchester United fans, Real Madrid may be about to step up their pursuit of David de Gea.

Iker Casillas was guilty of yet another an awful howler today. The Spanish goalkeeper gifted Atletico the lead in the Madrid derby, letting a straight-forward shot from outside the penalty area squirm past him. Casillas' got a hand to Tiago's effort, but was positioned poorly and couldn't stop it rolling into the net. https://www.youtube.com/watch?v=r5KhXBC_buA That set Atletico on their way to a stunning 4-0 in over their local rivals. Saul Ñíguez added a second after 18 minutes before second-half strikes from Antoine Griezmann and Mario Mandzukic made it a perfect day for Atletico. You can catch all the goals from what will go down as a famous win here: https://www.youtube.com/watch?v=f0MNYpAunDM