I remember that Chelsea 2-3 defeat in 1989 very well. It was an unusual day as united were playing at home (with the same kick off time irrc) to Forest in the Quarter Final of the FA Cup - it should be a sobering thought to united fans that if they'd won that game it could have been them, and not the Liverpool fans, in the Leppings Lane that April, not least because it was allocated to Liverpool in that fateful semi for reasons of geography.
At Maine Road was what was being billed as the promotion decider, between the two clear stand-out teams in the division. It was a dreary, rainy Manchester day and I remember it kicking off outside quite a bit. There was certainly a menacing atmosphere around the ground that you rarely experience any more.
On the pitch, Chelsea showed that they were a class above us - we were no match and the scoreline flattered us tbh. Gerry Taggart scored for us iirc, not sure who got the other. The game was also notable for the camera tracks along a decent length of the pitch at the front of the Main Stand, designed to follow the play as it moved up and down the pitch. A far cry from the modern, robotically controlled contraptions of today, it was propelled by two blokes pushing it along with a camera man sat on the back- all wearing waterproofs! I remember one particular moment where it followed Neil McNab trying to keep up with the Chelsea right winger flying towards the Platt Lane, and using every last reserve of strength, managing to just get close enough to clatter him across the touchline with an intention of going for the ball of absolute zero. Classic eighties TV!
As to the Chelsea support that day, it was huge. They filled the Platt Lane and the standing section next to it. Easily 8,000 I would say. They could certainly call on notable levels of support when required.
It's incredible to think that was only a quarter of a century ago. Both on and off the pitch it was another world and little did any of us realise that a result that day a few miles away at Old Trafford would set off a chain of events that would change the landscape of English football forever.