Youngs wary of Fiji threat
Tournament hosts England launch the World Cup against the Pacific Islanders at Twickenham on Friday.
"Fiji are a little bit of the unknown because they can do the unexpected," said Youngs of a side renowned for their ability with ball in hand.
"There's only so much prep we can do on them because they can do something out of nothing, that's the type of player they have.
"We'll have to make sure we're watertight in defence and force them to make errors and play too loose."
Much of the build-up has centred on the fact that England, Australia and Wales are all drawn in Pool A – the so-called 'group of death', with at least one of rugby's major nations to be knocked out before the quarter-finals as only two teams will qualify for the last eight.
But Fiji, who knocked Wales out of the 2007 World Cup in France, are the reigning Pacific Nations Cup champions and boast an impressive backline.
During the 2013/14 season, the Fiji trio of wing Nemani Nadolo (Crusaders), fullback Metuisela Talebula (Bordeaux) and centre Vereniki Goneva (Leicester), were the leading try-scorers in the Southern Hemisphere's Super Rugby, France's Top 14 and England's Premiership respectively.
Youngs, who played alongside Goneva at Leicester, added: "Niki is one of the best players I've played with simply because he can either run over you or step you.
"He makes you do the splits as you try to tackle him, simply because you don't know what way he will try to go.
"He's got all the ability, great hands and is a physical guy. He can be very physical, but also subtle with electric pace.
"Then there's Nadolo, he's a big guy so we don't want to get a big run up. There will be moments when there are four people on his back trying to drag him down, so we have to make sure we don't feed their belief by keep giving them the ball."
Youngs also highlighted the threat posed by opposing scrum-half Nikola Matawalu, saying: "Matawalu at nine is a real handful.
"He's probably the heartbeat of their team, giving up 50 kilograms on Nadolo, but equally electric and can do something special."
While England will be looking to make Twickenham something of a fortress, Youngs understands how England's headquarters ground can inspire opposition teams as well.
"Niki said it's a huge honour for them to play in the opening game in front of 82,000," Youngs explained.
"We won't underestimate them, they're here to win."
England, however, will be firm favourites on Friday as they have never been beaten by Fiji in a Test match.
After all the hype surrounding the tournament Youngs, who is set to win his 50th cap on Friday in an England team where brother Tom will start at hooker, is relieved that a match is now just days away.
"England are ready to go and we've been ready to go for the last couple of weeks," said Youngs, whose father Nick won six caps as an England scrum-half from 1983-84.
"It's been a long wait for a lot of guys, so we can't wait to get out there on Friday. There's a real edge and intensity about us, not nervousness, just excitement.
"We have a young group of guys who have no fear. They're too young to have any fear," added the 26-year-old.
"You can really sense the buzz around the country. Everyone knows it's coming now."
Agence France-Presse
