Arsenal's defeat at Liverpool on Sunday leaves them five points behind Chelsea in the Premiership table and with one win in eight games in all competitions.
Manager Arsene Wenger said his players were tired after their midweek Champions League draw at PSV Eindhoven, when they finished the game with nine men.
But are Arsenal's problems merely short-term or is there a crisis at Highbury?
BBC Sport asked football expert Alan Hansen for his thoughts on the key issues.
HAVE ARSENAL BEEN WORKED OUT?
Arsenal pass and move with pace better than any other team I have seen in English football - but there is a definitive way to play against them.
Teams no longer try to take them on at what they do best, but attempt to break up the way they play.
The opposition hustle and harry them to make sure they don't get into any rhythm and use a physical approach to disrupt their fluency.
When playing Arsenal you have to make the game scrappy.
Against this Arsenal have to battle hard for 55 to 60 minutes and then hope that their quality will take over.
But at the moment they are at a stage where their big players are struggling to make an impact upon games.
ARE ARSENAL SUFFERING A CRISIS OF CONFIDENCE?
People said ahead of Sunday's game that it was a good time to play Liverpool, but I thought it was also a decent time to be playing Arsenal.
The Gunners had one shot on target in 90 minutes and that tells its own story. Six weeks ago Arsenal were hitting four and five past just about everybody and confidence was sky high.
All of a sudden - after just one win in their last six Premiership games - there is a lull in that confidence.
The only way to get it back is by pulverising somebody.
ARE ARSENAL TIRED?
Manchester United, Chelsea, Liverpool - they are all in the Champions League as well as Arsenal.
They are all playing a lot of matches, they are all a bit tired and carrying injuries.
Everybody has to juggle their formations and personnel.
Manchester United have played a weaker team this season on more than one occasion when Sir Alex Ferguson might have wanted to field a stronger side.
What he has done is make sure he gives certain players a rest at key times.
When Arsenal were on their long undefeated run there was no talk of tiredness and they cannot use that excuse now.
WILL ARSENAL BOUNCE BACK?
Unfortunately for Arsenal they are in a slump - but they always say that the great teams will come out of it.
Arsenal are still an unbelievable team - you do not go 49 Premiership games unbeaten without being a brilliant side.
They now need to show strength of character and prove a few people wrong.
If you want to be one of the great dominant teams you have to win back-to-back championships or the championship and the European Cup in the same season.
Manchester United have done it and so have Liverpool.
We will have to see what happens to Arsenal but the big thing at the moment is that Chelsea are exerting a lot of pressure on them.