Arsenal manager Arsene Wenger admitted "something has gone" within the team after they came off second best against Stoke in a 3-1 defeat.
Goals from Kenwyne Jones and Jermaine Pennant put the hosts in control in the first half and, even when Robin van Persie pulled one back late on, Jon Walters replied immediately to snuff out any thoughts of a comeback.
It ended any outside chance the Gunners had of forging a late run to the top of the table.
"Something has gone - you can see that," said Wenger. "It was a disappointing performance. The competitive level for Stoke was higher than ours and overall I think we lost the game because Stoke defended much better than we did, with much more purpose.
"Basically, there is not a lot to say."
Last weekend Arsenal beat leaders Manchester United to reignite hopes of catching Sir Alex Ferguson's side, but those chances were quashed in clinical style by a committed Stoke team who could have been forgiven for having their minds elsewhere with an FA Cup final appearance just six days away.
"That is the Premier League. If you don't turn up it is the same competitive spirit in every game and you can lose everywhere, especially at Stoke," Wenger said.
"Stoke defend well and make it difficult for you and the most important thing is not to be 1-0 down - and that is what happened with the first free-kick (for Jones' goal).
"In a game like that we turned a lot around but we did not penetrate enough and we were not dangerous enough."
The match marked Aaron Ramsey's first return to the ground to face Ryan Shawcross after sustaining an horrific double-fracture of his leg in a tackle with the Potters captain in February last year.
Wenger said he felt the midfielder, who was replaced at half-time, coped well.
"He did all right," said the Frenchman. "He was not scared but he is still short (of match fitness). He has not played enough games.
"It was just a tactical move (to take him off). We were 2-0 down and we had to go for more penetration.
"We had a lot of possession but not a lot of progression and football is a good balance between the two."
Stoke boss Tony Pulis said he could not fault the approach of his players with a Wembley final against Manchester City just around the corner.
"The biggest compliment I can pay our players is that with a cup final only six days away their attitude and commitment to trying to win a game was 110% and that speaks volumes for them," he said.
"We have played one of the best teams in the country, a team which is competing against the likes of Barcelona and other great teams in Europe, and we have beaten them quite comprehensively."
The day was not without its downside, however, and a knee injury to Robert Huth will be a worry over the coming days.
"Robert is the one we are a bit concerned about but we won't know until tomorrow," added Pulis, who said injured winger Matt Etherington would be assessed day by day and be given until an hour before kick-off next weekend to recover from a hamstring problem.