Wilkinson and Woodward celebrate England's 2003 World Cup win
England v South Africa
Saturday, 20 October
Stade de France, Paris
Kick-off: 2000 BST
Live on BBC Radio 5live and the BBC Sport website
Former England coach Sir Clive Woodward says Jonny Wilkinson's presence is critical as the world champions chase a historic second straight World Cup win.
"Jonny is the difference for England, let's make no bones about it," Woodward told BBC Radio 5live.
"The England team looks very strong now with him in that position.
"But take him out, put any other player there and you really couldn't see England winning without him - he is that important to the whole team."
The 28-year-old fly-half, who kicked the winning drop-goal in the final minute of extra-time in the 2003 final, missed England's 36-0 pool defeat to the Springboks with an ankle injury.
But he recovered to lead the side to victory against Samoa and despite not being at his best, has delivered when it has mattered.
Jonny is an iconic figure and England are lucky to have him
He kicked a late penalty and drop-goal against France last Saturday to seal England's place in the decider and give them a chance of retaining their World Cup crown.
"There's no doubt Australia and France were almost in awe of him - he's that big a personality on the field," Woodward added.
"As the clock ticks down, if England are in sight of the scoreline with 10 or 15 minutes to go, the more Wilkinson comes into play.
"When teams fade in the last 10 minutes, he has taken the game by the scruff of the neck and delivered. He is an iconic figure and England, and Brian Ashton, are very lucky to have him in the team.
"The opposition know that if they make one mistake in their own half and give away a penalty he is going to score against them, or they are going to be on the end of drop-goals.
"It makes teams play in a different way. If Australia and France had their time again I am sure they would both play totally differently.
"They tried to nullify the Wilkinson factor by kicking away so much ball which really played into our hands, because we have good players back there like Jason Robinson and Paul Sackey and Josh Lewsey.
"It alters the way teams play just having Wilkinson on the field."
Despite the startling ascent of Ashton's men in the last few weeks, Woodward believes their progress has come in spite of - rather than because of - the preparations that led up to the tournament.
"We arrived at the tournament in poor shape compared to 2003 and whatever happens on Saturday, I hope England's preparation over the next four years is far, far better than the last four years," he added.
"It's not fair on the players because as an England player you may only get one chance at winning a World Cup and you want your union and your coach to deliver the best possible programme that gives you every chance of winning.
"England have not played the prettiest rugby but it's just so effective and you wouldn't want to play against that team at the moment.
"There is a real momentum there and a fantastic team spirit and attitude. In team sports that can take you a long way."