For Jose’s fan club it was a day to remember.
For Arsene’s, it was yet another dismal one to forget, and yet it all might have been so different.
Chelsea, let’s not forget, are the side who’ve made the dismal start to the season, and this was only their second win in six.
The anger Arsenal fans will be feeling will be coupled with a sense of injustice that Diego Costa stayed on the pitch.
What will have made it worse was the role he played in the Gunner’s own first red card, after Gabriel interceded when the referee appeared perfectly happy not to, as the Brazilian played patty-cake with Laurent Koscielny’s face.
Gabriel lashed out on his team-mates behalf, and he walked just before half time.
For Costa, who thrives on moments like this, that was “job well done.”
That wrapped up a first half that had been pretty even.
On 53 minutes the game changed when Kurt Zouma headed home the opening goal.
Mourinho had surprised some by including him ahead of John Terry, but his overall performance was excellent and it was capped by his getting on the scoresheet.
When Santi Cazorla was sent off in the 78th minute for a second bookable offence, the writing was on the wall here.
Arsenal, with 9 men, fought gamely on for the remaining twelve minutes but it was never likely to end other than it did; with Chelsea smashing home a second in the last minute, when a Hazard shot hit Callum Chambers on the way to the net to wrap up the points.
Man of the match:
Mourinho, being typically cheeky, said Costa.
Kurt Zouma, though, looked fantastic throughout and got on the scoresheet.
The decision to field him was fully vindicated, and will continue Chelsea’s amazing run against their rivals; five clean sheets in a row against them in the EPL, unbeaten against them in the last eight.