UNDER-PRESSURE England captain Alastair Cook will pay little heed to the opinions of those "outside" his dressing-room - such as Kevin Pietersen.

An indifferent performance from England's batsmen in particular - with the exception of Cook’s Essex team-mate Ravi Bopara who hit 51 - condemned them to an eight-wicket defeat against Sri Lanka at the Premadasa Stadium, where the hosts completed their task with more than 10 overs to spare in Saturday's rain-reduced match.

Cook, 2-0 down with five matches to go, is therefore already perilously on course to lead his country to his sixth consecutive one-day international series defeat.

Within seconds of England's inadequate 185 all out being overhauled by Kumar Sangakkara (67no) and Mahela Jayawardene (77no), Pietersen was already in contact via Twitter - in the knowledge that even though Cook is not part of the social media network, he would soon get to hear the content.

Cast in the role of supporter only after his sacking by England nine months ago, controversial batsman Pietersen sent his personal advice for Cook to step aside with the World Cup fast approaching in Australia and New Zealand.

"Dear Alastair, if you care about England's chances this winter, pls resign and just concentrate on Test cricket," he wrote.

Shortly afterwards former England captain Michael Vaughan, a notably vociferous critic last summer of Cook as an ODI batsman and captain, also made his feelings known again on Twitter.

"It's not too late to change.... It's not too late to compete.... But England won't if they stay the same ..." Vaughan told his followers.

Responding to Pietersen only, Cook said: "It's a good job I'm not on social media!"

Pressed, he added: "People are totally entitled to their view.

"That's the nature of the beast when you're on the outside.

"People believe what they want to believe.

"In our dressing-room, we've got to stay strong as a group.

"We're the guys who have the honour of playing for England at this moment in time, and we have guys who have the opportunity to turn it round - not other people outside."

Cook's poor form continues - he has not made an ODI hundred in 41 innings, stretching back more than two years - and he said: "I think you feel the heat when you're not scoring runs.

"If you have two games at the start of a tour, and don't score them, you're naturally going to start feeling that.

"That's only natural. (But) I've just got to do what I keep doing, believing in myself, doing my basics right."