Chelsea boss Andre Villas-Boas says they turned in their worst performance of the season in defeat at Everton.

Visiting supporters reacted with chants of, 'You don't know what you're doing' when the Portuguese substituted Michael Essien in the second half.

Villas-Boas, whose predecessor Carlo Ancelotti was sacked at the same ground last year, said: "I think today was one of our worst games of the season, if not the worst.

"In our performance today we are short of anything positive.

"It is a difficult day for us, we take out a lot of negatives from this game."

Speculation over Villas-Boas' future has increased in recent days with Chelsea owner Roman Abramovich twice visiting the club's training ground.

Villas-Boas claims that did not affect the performance.

"You don't expect any effects from that," he said. The Portuguese was also unmoved by the negative chants against him and claimed he could understand some of the frustration.

He said: "It is part of the job. At the moment we are sitting fifth in the league and it is not enough for us."