Sir Clive Woodward has warned Stuart Lancaster "one stupid tweet" from any of his players could derail England's World Cup bid on home soil.
The 2015 tournament hosts launch their campaign against Fiji at Twickenham on Friday week, and England's 2003 World Cup-winning coach has revealed he has handed current boss Lancaster some words of advice ahead of the global battle.
Woodward categorically cites social media as the chief pitfall.
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"It's the new enemy," the 59-year-old said, speaking in this week's Radio Times about the Smartphone. "We didn't have to worry about it in 2003.
"I've had the conversation with Stuart Lancaster. Don't let the players be distracted. It could be the media, their family, sponsors, ticket requests, anything.
"One stupid tweet, one ill-judged video out on social media - if you allow one player to be distracted, it can affect the whole team, and it can all come tumbling down."
England have reportedly handed their World Cup squad social media guidelines, keen to avoid any unnecessary distractions.
Woodward believes home advantage hands England a huge boost, claiming France should still be aggrieved about losing 8-7 to hosts New Zealand in the 2011 World Cup final.
"If I had been the coach of France in that World Cup, I would still be apoplectic to this day," Woodward said.
"If that final had been refereed properly, France would have won."