Manchester City players gathered around a fallen Sergio Aguero when he was struck down in 84th minute of the derby by a Fellaini headbutt.
Video of tragic incident.

Marouane Fellaini summed up in one gif. pic.twitter.com/PNkpler2Wv

— Mike Sanz (@mikesanz19) April 27, 2017

Fellaini,as a result got his marching orders,and Sergio Aguero recovered miraculously shortly afterwards.
Mourinho had the following to say about the red card incident.
“I have just three details.Marouane says that it’s a red card because it’s Marouane. Martin Atkinson [the referee] told me that in his opinion it’s a red card, but I saw Aguero in the tunnel with no broken nose, no broken head and his face is nice as always, so I’m not so sure.
It was the high point of the game which ended in a goalless draw.Mourinho,hampered by the absence of Zlatan and other injured stars resorted to his time tested tactic of the parked bus
City could not find their way past the bus despite superiority in numbers for the last 10 minutes or so.
They remain in fourth place, still a point and a place ahead of United in the race for a top-four finish and Champions League qualifying spot, and United have a very impressive run of being unbeaten in 24 league games.
However they may yet pay dearly for Fellaini’s foolishness.
United,already missing Zlatan,will be without aerial fire power for the next few crucial games.