I was at the Manchester United vs Manchester City match today. It's not the end of the world, but it comes as a shock when you haven't seen anything like this in 80 years. I now know what Arsenal fans must have felt like when I watched them demolished 8-2.
Like the Arsenal fans, the Old Trafford faithful sang on. Outside the ground, walking away, there was a deathly hush. We're not used to this. Nor is the manager, who said he had never had such a bad defeat in his career. Nor are the players, as you could see, even at 4-1.
It's not the end of our title hopes; far from it. It's three points lost; possibly a six-point swing against our most likely title rivals, in which case, with a 10-goal swing in goal difference, it's effectively four points lost.
As Arsene Wenger will understand, you don't suddenly become a bad side. No doubt the anti-United brigade and the doomsday merchants will come out with all the statements about how badly we played last year. So Chelsea, City, Arsenal and Liverpool all played worse, guys.
The truth of the matter is that there has been an evening up process in the Premier League over the last few years, with one exception: Manchester City.
I will confess that when I saw Sergio Aguero's first match for City, I became deeply concerned, because for the first time in as long a I can remember, City are our most dangerous rivals. And so today proved.
All the talk on the radio was that United's midfield was overrun and all the clamour for buying every midfielder under the sun has re-emerged.
Yes the City midfield finished stronger on the day, but that wasn't the only or even the main reason why United lost.
Here are six others: