Carlo Ancelotti has pledged to eradicate the dreadful defending that is threatening to increase the pressure on the Italian after second successive Premier League defeat away from home.
Saturday's 2-1 loss here to Aston Villa combined with Manchester United's win over Bolton saw Chelsea surrender top spot in the table.
Defeat at Villa Park meant six of the eight goals conceded by Chelsea this season have come from set plays, evoking memories of the defensive problems that ultimately ended Luiz Felipe Scolari's reign at Stamford Bridge.
James Collins delivered the killer blow with his first goal in four seasons to extend Aston Villa's unbeaten home run to six games and heighten optimism that Martin O'Neill can unsettle the established order.
But the worry lines on Ancelotti's forehead will become more pronounced with further performances like this, despite Didier Drogba's seventh goal of the campaign gifting Chelsea the advantage.
Richard Dunne capitalised on dreadful defending to equalise and Collins pounced early in the second-half to condemn Chelsea to another alarming defeat on the road.
Two seasons ago Chelsea owner Roman Abramovich stormed out of Villa Park in a rage after a 2-0 defeat, with then manager Jose Mourinho sacked days later.
Italian boss Ancelotti is under no immediate danger but the alarm bells will surely be ringing already following Chelsea's insipid defeat at Wigan.
And ahead of their Champions League game with Atletico Madrid on Tuesday, it promises to be a busy few days on the training ground as Ancelotti works on his problems.
He said: "I am disappointed because Chelsea played a good match. We lost this game on the set plays and I don't like to lose games on set plays.
"Aston Villa did a very good job. On the set plays we need to do better because we can. Those are the questions from this match.
"The first goal was from a set play and we need to improve on the situation. We have to pay more attention and more concentration in the box.
"We work every time on the set plays but we have to improve. We need more focus. At Wigan the first goal was the same.
"When we lose a game for sure we are not happy but I think that until this moment the team has played very well and done a very good job.
"But there are things we can improve on," the former AC Milan manager added. "I'm sure the players will do this in the next game."
This was no more than Villa deserved, however, and O'Neill possesses a vibrant squad that could deliver on their mission to gatecrash the Big Four - or Five, as it may be now.
O'Neill believes he has his best squad yet after three years in charge and this win came after an earlier victory over Liverpool.
"We've got some really good players and a decent squad with players that aren't getting into the side," said former Northern Ireland midfielder O'Neill.
"It's the strongest we've been for three years. There's only eight games gone, we've done fine and we've played three of those games who will be in contention and we've been okay.
"I'm absolutely delighted, I thought we played brilliantly. We had to defend in the second-half, they came at us strongly but we saw it through.
"The overall view of the game was that I thought we were splendid," O'Neill, previously in charge of Scottish giants Celtic, said.
"We've beaten, in my view, a team that if anybody finishes above them they will win the Premier League."