Manchester United were comprehensively beaten by noisy neighbours Manchester City on Saturday afternoon.
Pep Guardiola's side were the dominant force at Old Trafford, the Premier League champions strolling to a 2-0 victory.
An own-goal from Eric Bailly - who was hooked at half-time - got the ball rolling for City and just before the break, Bernardo Silva grabbed a second for the visitors.
United's defending for the Portuguese playmaker's goal was laughable, with Harry Maguire and Luke Shaw both ball-watching and allowing Silva to tap home from close-range.
City went into cruise control in the second half and they still could have extended their advantage on a number of occasions.
On the day, Guardiola's men were simply better and hungrier, the latter summed up in one moment involving Aaron Wan-Bissaka.
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During the second half, the United right-back prompted the loudest boo heard around Old Trafford all day when he inexplicably bottled a 50/50 near the City penalty box.
Fans will accept being dominated by a far superior team, but they will never let players pulling out of tackles slide.
Take a look at footage of the incident here...
Video: Wan-Bissaka bottles a 50/50
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Sorry Aaron, but that's just simply not acceptable.
"That's the largest boo we've seen in-game," United legend Gary Neville said on commentary with regards to the incident and he was bang on the money.
If you want to get a foothold in a derby when you're the weaker side on paper, you have to give 110% for the entire 90 minutes, which Wan-Bissaka certainly did not do.
He's flattered to deceive in a United shirt for quite some time now, with his inability to be effective in attacking areas becoming a rather sizeable issue for Ole Gunnar Solskjaer.
To make matters worse, Wan-Bissaka is also struggling defensively right now and was caught out position a number of times against City.
The problems continue to mount for Solskjaer and the fact he was taught a footballing lesson by Guardiola on Saturday may be the final straw for those above him.