It was not just the end of an era, but the end of an aura.
This will be forever remembered as the game when David de Gea finally lost his grip, the Manchester United keeper’s steady decline has seen him go from best in the world to liability.
We should not lose sight of the fact that Chelsea thoroughly deserved their victory over a tired, lacklustre Manchester United who made the fatal mistake of prioritising a top four place over a trophy.
But Chelsea also benefited from two more shocking errors from de Gea who was solely to blame for the first two goals.
You have to add that to a catalogue of mistakes against Watford, Everton, Bournemouth and Tottenham.
With every mistake it is becoming increasingly harder for Ole Gunnar Solskjaer to defend his No.1.
But de Gea is simply not the keeper he once was.
He has long since been usurped by the likes of Ederson, Alisson and Jan Oblak.
The irony was that Solskjaer rested and rotated his squad with more than half an eye on the race for a top four place and Wednesday’s home game with West Ham but stuck with de Gea over Sergio Romero and how he must regret that decision now.
Chelsea seized on United’s sloppiness, their tiredness and, ultimately, you quickly get found out if you make the mistake of different priorities even at this stage of the season.
Frank Lampard’s men were sharper, hungrier and ready to take advantage as their tireless work rate in midfield, Olivier Giroud bullied United’s defence set up a repeat of the 2017 FA Cup final.
The bookies had the odds in favour of an all Manchester final before this weekend.
But both semi finals have provided an upset and Lampard should now begin to get the credit he deserves after a remarkable first season in Premier League management.
This was Chelsea at their best, they were better from the start as United’s gamble of resting players, switching to a back three did not work as Lampard outsmarted and outwitted Solskjaer.
A largely unforgettable first half changed in the 45th minute when Harry Maguire and Eric Bailly were involved in a sickening clash of heads.
Maguire played on after lengthy treatment but, very alarmingly, Bailly collapsed as he left the pitch and needed medical attention and to be stretchered off with nine medics swarming around him.
On came Anthony Martial for Bailly, United switched to a back four and maybe they had lost concentration after the shocking incident and, 11 minutes into first half injury time after the lengthy stoppage, Chelsea deservedly went ahead.
Cesar Azpilicueta got forward down the right, put over a low cross and Giroud drifted across Victor Lindelof and steered the ball towards goal but it should have been a straightforward save only for de Gea to let it go through him.
But if you thought that was bad then even worse was to come. Just a minute after the restart, Brandon Williams’ sloppy square pass let in Mason Mount.
Chelsea midfielder Mount let fly from 25 yards and the ball squirmed under de Gea’s body. But that is the point – Mount probably would not have even tried his luck but for the fact de Gea is now seen as a weak link.
United brought on the big guns with the likes of Paul Pogba and Mason Greenwood being introduced.
But there was no way back.
It got even worse after 74 minutes when Marcos Alonso put over a low cross and Maguire diverted the ball into his own net at the near post.
There was a little consolation after 86 minutes when Bruno Fernandes scored a penalty after Callum Hudson-Odoi tripped Martial.
It was the first time Fernandes has lost in a United shirt and United’s first defeat in 19 games.