IF Mikel Arteta had not worked it out already after two games as a manager, football can be a very cruel game.
For the first 80 minutes at the Emirates there were so many signs of encouragement for Arsenal but, in the end, the same old problems that have plagued them for years came back to haunt them.
In the first half they looked compact and tight at the back – not something that can be said too often.
The whole team appeared organised for large parts and it looked as though they had a different attitude.
They put in a huge amount of effort, which they have regularly lacked in the past.
Then, with just seven minutes to go, the old Arsenal came back to bite and they self-destructed.
Firstly, you can’t legislate for individual errors with Bernd Leno, who has rarely been the culprit, gifting Chelsea an equaliser.
Then, instead of settling for 1-1 which would have been a good result, they went charging up the pitch at the end and left themselves wide open at the back.
Even then they could have stopped the winner, with Shkodran Mustafi needing to get tighter to Tammy Abraham.
One thing Arteta will now definitely know is that he desperately needs to bring new defenders in if they are to kick on.
Arsenal will complain that Jorginho should have been shown a second yellow card for pulling Matteo Guendouzi’s shirt.
Nobody could have moaned if he was sent off but Chelsea battered the Gunners in the second half in terms of possession and attempts at goal and Frank Lampard deserves huge credit for turning the game around.
Chelsea were awful in the opening 45 minutes and something had to change.
He hooked Emerson for Jorginho after 34 minutes, bringing an extra man into midfield.
It certainly stopped the tide and, after the break, they were by far the better side.
They have now beaten Tottenham and Arsenal in their last two away games, which would normally be a cause for celebration.
But after losing to Bournemouth and Southampton at the Bridge, the Blues really need to sort their home form out.
They have inexperience running through their team so up and down results can be expected.
However, if they can work out how to break down teams who sit back, then they will make the top four.