England skipper Chris Robshaw has demanded composure and discipline by his players when they face Wales with the Six Nations Grand Slam on the line.
Stuart Lancaster's England stumbled to a 18-11 Twickenham win over Italy last weekend, but were often wasteful with the scoreline in sight.
They can not afford any slip-ups in front of a hostile crowd in Cardiff on Saturday (kick-off 1700) and the pressure will be on with 10 of England's side playing a Test at the Millennium Stadium for the first time.
It has been a decade since Grand Slam glory and Robshaw said: "When you come to a place like Cardiff, you might get one or two chances, and we've got to make sure we are good enough to make it count, whether it is the first minute or the 80th minute.
"It is one thing saying it and it is another thing doing it. That is the challenge we have. Of course, everyone wants to go out there and win, but it is about how you go about it and breaking it down into the smaller, finer detail.
"We can't afford to switch off at all or lose concentration or lose our composure. If we get a chance in the first or 80th minute we need to be mentally prepared and right up for it.
"It's a huge occasion for English rugby, and there is a massive opportunity out there for us if we can go out there and hopefully deliver on what we've talked about."
England will still secure a second title in three years if they lose by six points or less, while their hosts will retain their title if they win by eight points, or seven if England do not score three more tries than them.
"We know what happens if we win, and we know what happens if they win," Robshaw added.
"Both teams know exactly what they want to get out of this game and it is about showing that intent from the off. Both sides will want to get off to a great start and build momentum from that.
"We've been to intimidating places before, the likes of Ellis Park (Johannesburg), and Wales is definitely up there. People speak about it as probably one of the best places to actually go and play rugby.
"If you give the crowd an opportunity to get into the game in the first 10 minutes, then it's going to be a long old afternoon, as we found at Ellis Park last summer, when we were 20 points down in 20 minutes.
"It is about making sure that in the warm-up we soak up what it is going to be like, and make sure when that first whistle goes we are mentally prepared and ready to give it our all."
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