Will Carling says England are facing one of the toughest Rugby World Cup pools in history and need to show the mental strength of more experienced players to win the tournament they are hosting.

Stuart Lancaster's side open against Fiji at Twickenham on Friday with Wales, two-time world champions Australia and Uruguay to come.

After securing an impressive victory against Wales in the Six Nations opener last February, England's grand slam hopes were ended by a subdued performance in Ireland and that worried Carling.

How important is home advantage? Will Carling experienced playing in a home World Cup and captained England to the 1991 final, where they were beaten 12-6 by Australia at Twickenham. He knows what the players can expect with the pressures of a home crowd - particularly with so much at stake. "What are these guys going to experience? Hopefully a huge amount of support and desire from the English fans," Carling told ESPN. "It's so much bigger now than it was in 1991. "The build-up is on a completely different scale. Having said that, once the World Cup started in 1991 and we were lucky enough to win a few games, the interest and attention the guys got was much greater than normal. "There's a comfort playing at Twickenham. You know the stadium, you know the hotels - there's a comfort in your schedule being the same as it always is. It's your patch. It's up to coaches, players and management to make sure that they get away from the pressure and are allowed to get away from it. "They need to make sure they unwind, let off steam during the tournament - you can't maintain the necessary intensity for seven weeks."

"Consistency will be key," Carling told ESPN. "Even in the Six Nations, the second half performance against Wales in Cardiff was exceptional. Yet their performance against Ireland was not exceptional -- there have been fluctuations.

"For England to win a World Cup -- we are capable of beating the best sides in the world -- we've got to be able to put two or three of those exceptional performances back to back.

"Understanding how difficult it is to be mentally at the right level every time -- maybe that does come with experience.

"That is the thing that some of the players still need to learn and I'm hoping they learned that in the Six Nations. Going away to Wales as an English team is about as difficult as it gets -- and they did brilliantly. They then went to Ireland and weren't at the same level of intensity. They have to learn to play at that level every time.

"They're in a pool that is as hard as any World Cup pool has ever been. So it's not just a home World Cup, it's a home World Cup with a genuine possibility that England might not get through the pool stages."

In naming his final 31-man squad, it was clear head coach Lancaster had plenty of talent at his disposal. However, questions were raised about a collective lack of experience.

Lawrence Dallaglio, who succeeded Carling as England captain, claimed the current crop have yet to go through a "tough" experience -- such as the one he believes helped mould England's 2003 World Cup winning squad.

Carling, who won 72 caps and helped guide England to successive Grand Slam victories in 1991 and 1992, shares similar concerns.

"Lancaster has done very well and uncovered a huge amount of talent," Heineken ambassador Carling said. "Where we haven't done as much, is that we haven't really had the time for certain combinations to bed down.

England impressed against Wales in the 2015 Six Nations - but underperformed in defeat to Ireland David Rogers/Getty Images

"George Ford has only just come in and has been exceptional, same with Jonathan Joseph and Anthony Watson. We have some very exciting players in the backs, just not with much experience.

"We've got two world class front fives. Genuinely, we've got great forwards and I think England are going to be very, very hard to beat at Twickenham. If we're being honest, most of the big teams will be thinking 'Yep, we'd prefer to avoid them'.

"We knew when this World Cup was coming. We are a young squad, but that's not a reason why we shouldn't do well. There are lots of very, very good young players in world rugby.

"You look at teams that have won World Cups and they're usually very experienced. So if you're going on what's happened before, you'd look at it and come 2019, these players are going to be an experienced crop. That makes it more realistic that they'd go on and win a World Cup - but I still wouldn't bet against England."