Former captain Martin Johnson believes England's "extraordinary" victory over Australia has already helped make the 2007 World Cup the best ever.
England's win over Australia was a huge upset
But he warned Brian Ashton's side they must sharpen their attacking edge to overcome France in the semi-final.
"We need a bit more composure because when they look at the tape, they left two or three tries unscored against Australia," he told 5live Sport.
"If we want to win the next one, they will have to score a couple of those."
Australia just didn't have that physical edge. They got into a game with 20 minutes to go they didn't want to get into
Johnson, who called it a "privilege" to witness Saturday's stunning upset in Marseille, also believes England will not enjoy the same level of forward superiority they had over the Wallabies when they face the French.
"We are not going to dominate a team like France as quickly as we did Australia," he said.
"They can scrummage, they are far more proficient, and any advantage will take time to get. It won't be as big as what happened against Australia.
"They were poor scrummagers, but there is no team left in the tournament who have that weakness."
Nevertheless, Johnson, who led England to victory in Australia four years ago, drew great encouragement from the manner of England's victory and the growing belief surging through the team.
"We had the burden of expectation in 2003 that this team don't have, but they have had an unsettled team, injuries and all these other things to deal with," he noted.
"It would be a far more unexpected achievement if they reach the final. It is extraordinary, but it is extraordinary what has happened at this World Cup in general.
"In terms of the number of games that have been fantastic entertainment, I think it has already been the best World Cup ever, and I don't say that lightly. And we have still got three more huge games to go."
France's win over New Zealand made the headlines
Johnson, speaking as an ambassador for tournament sponsors Visa, admits he, like most observers, did not expect England to send Australia packing.
And he believes they will need to recreate the same mentality they took into the game for Saturday's semi-final clash with France, who could suffer a "comedown" after their own upset victory over New Zealand.
"England had the right mentality going into the game," he added.
"They thought 'we have nothing to lose, we will give it a go' and I was very encouraged from the first minute by the way they played.
"Australia just didn't have that physical edge. They got into a game with 20 minutes to go they didn't want to get into.
"Saturday will be psychologically fascinating again because France have experienced huge emotions - losing to Argentina, coming back and qualifying, then beating the All Blacks. But can they back it up again?
"Traditionally their best performances in the tournament have been followed by a fairly flat one, albeit against very good opposition.
"They have come down to earth, but now they are going home, where previously things looked very black for them, and now they look incredibly bright.
"The All Blacks are out, Australia are out, they have to beat England, who they beat twice in August, to get to the final.
"So England need to find that edge again and use whatever motivation they want to say 'we can do this'."