Chelsea manager Andre Villas-Boas described the 2-0 defeat at Everton as one of their worst performances of the season and insisted it was his fault.
Villas-Boas said: "It was one of our worst displays - if not the worst. We saw a brave Everton that showed aggression and great commitment.
"Our players showed exactly that and, if there is one defeat that the manager should take the blame, it is this one.
"I'll go back to my pre-planning and decision-making."
The Blues, who have slipped to fifth in the Premier League table, fell behind inside five minutes and rarely looked like getting back into the game at Goodison Park.
Steven Pienaar took advantage of a fortunate break to crash home the opener.
Frank Lampard wasted Chelsea's best opening when he shot wide and Denis Stracqualursi sealed the win after being sent clear by Landon Donovan.
Chelsea are now without a victory in four league games and sit 15 points behind leaders Manchester United.
"Fifth in the league and it is not enough for us," Villas-Boas added.
"After the goal we managed to get the ball on the ground and managed to have the initiative and create some problems, but we weren't objective enough in our possession to create more danger.
"One of the things we always have is that we manage to create opportunities and this wasn't the case today. We fell very short in terms of goalscoring opportunities when a response was needed."
Toffees boss David Moyes was thrilled with both his side's commitment and quality, which ensured a third straight home victory in all competitions.
"Recently we have done very well but today capped it," Moyes said.
"We played well, it was hard and Chelsea were good but we did what we do at Goodison. We are hard to beat.
"It was a great start [for the team] and a great start for Pienaar coming back and scoring. Chelsea came into it and had one or two chances and we had to ride our luck a little bit but we kept at it, got to half-time and got the second goal in the second half.
"We blocked and defended well and did all the things you hoped you would do. Great credit to the players, they are beginning to show what they are about. They are beginning to find the form they are capable of, and I think we can play much better and I am looking forward to that."