The race for Europe is wide open again after Arsenal somehow pulled off an unlikely win at Stamford Bridge.
It was a bizarre, crazy game summed up by Jorginho’s catastrophic mistake which led to Emile Smith-Rowe’s first half winner.
But suddenly Chelsea’s place in the top four does not look so secure and two meetings with Leicester in the space of four days will hold the key to their season.
Chelsea boss Thomas Tuchel faces Leicester in Saturday’s FA Cup final and then a rematch with Brendan Rodgers’ men at Stamford Bridge next Tuesday.
Whoever slips up next week could still let in Liverpool as things begin to get complicated when they had looked so easy for Chelsea before the game… beat Arsenal and a place in the Champions League is as good as theirs.
Meanwhile, Arsenal move up to the giddy heights of eighth place in the table, they could yet snatch a place in the Europa Conference League which seems one hell of a drop down from their European Super League aspirations.
What must frustrate the life out of Mikel Arteta is that this was far from being a brilliant performance, anything but as they parked the bus and just refused to let Chelsea past.
But it showed plenty of defensive defiance and determination, the players battled and showed heart and they have not done that on nearly enough occasions this season.
This was, incredibly, their first win at Stamford Bridge in 10 years; they completed the double over their London rivals and, just when you thought Chelsea were going in one direction and Arsenal the opposite, this season surprises you again.
Chelsea must be kicking themselves as they twice hit the bar in the 90th minute, had an effort ruled out for offside through VAR and yet this had all the hallmarks of a team with other things on their mind.
It was only Tuchel’s third defeat in 26 games in charge in the last four months since taking over - and it came with the sort of defensive mistake he thought he had cut out of Chelsea’s game.
The only goal came after 16 minutes courtesy of a Jorginho blooper as he did not look before playing a back pass, Kepa Arrizabalaga was out of position, scrambled back and the Chelsea keeper somehow clawed the ball back and stopped it going over the line.
But there was Pierre-Emerick Aubameyang to pull back the loose ball and Smith-Rowe just about scuffed his shot into the net off a post.
What a gift.
Chelsea pressed and pressed but found Arsenal’s reshuffled back three in resilient mood. For once they refused to buckle. Mason Mount saw an effort saved by Arsenal keeper Bend Leno and another blocked by the outstanding Rob Holding.
Chelsea thought they had found a way after 61 minutes when Christian Pulisic bundled the ball into the net only for VAR to over rule it as the US winger was offside.
Tuchel threw the kitchen sink at Arsenal, throwing on Callum Hudson-Odoi and then also ex-Gunners striker Olivier Giroud in the closing stages as Kurt Zouma also went up front as an emergency centre forward.
It was Zouma’s looping header which gave Arsenal their biggest scare of the night as Leno back peddled and pushed the ball onto the bar.
The ball fell to Giroud who seemed certain to score in the final minute to deny his old club only to crash his effort against the bar again.
It was an almighty let-off for Arsenal while Chelsea will now be sweating on European football which is an unwanted distraction ahead of the Champions League final.
Sign up to the Mirror Football email here for the latest news and transfer gossip.