Steven Pienaar gave Everton a fifth-minute lead, before Denis Stracqualursi sealed the three points when he completed a sweeping Everton move and tucked his finish past Petr Cech with 13 minutes left.
“It was one of our worst displays of the season, if not the worst,” Villas-Boas told the BBC. “Today we weren’t ourselves and couldn’t express ourselves.
“We saw a very very brave Everton that showed their aggressive and commitment to win this game. I think our players also showed commitment, and if there is one defeat which the manager should take the blame for, it is this one.
“So I’ll go back to my pre-planning and my decision making, because maybe it wasn’t right today.”
Pienaar made the breakthrough after five minutes when the South African midfielder seized on a loose ball and fired past Cech to put the home side in front.
Chelsea lacked any cutting edge as Fernando Torres cut a frustrated figure once again, and despite Villas-Boas introducing Romelu Lukaku and Florent Malouda in the second half, the visitors were unable to test Toffees goalkeeper Tim Howard.
Stracqualursi then completed Everton’s victory in the 71st minute, running onto Landon Donovan’s through-ball and placing his finish to the left of Cech.
“We played well today,” said Everton boss Moyes. “It was hard, Chelsea are a good team. But we are difficult to beat at Goodison Park.
“It was a dream start. Great start for Steven Pienaar to come back and score a goal for us.
“The players are beginning to show what they are about. The strange thing is we can play much better than we are at the minute, but we’re winning.”
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