Former South Africa international Robbie Fleck insists defeat to England in the Rugby World Cup final would be a "disaster".

The Springboks humiliated Brian Ashton's men with a 36-0 victory in the pool phases but that defeat proved a turning point for England, who have gone on to defeat Australia and France in the knockout phases to clinch a place in Saturday's final in Saint Denis.

Jake White's side are the only side yet to be defeated in the competition after beating Argentina in the second semi-final last night.

Asked on Radio Five Live what defeat would mean to his country, Fleck replied: "It would be disastrous. It would be a day of mourning for the country.

"We really have performed well coming up to this event and there is a lot of expectation from a South African point of view. To beat England 36-0 and then lose to them would be a disaster for all concerned.

"I don't think the South Africa team have to think about that. They really have matured over the last four or five years under Jake White. It's going to be an extremely tough match.

"England have improved every match and Jonny Wilkinson is a huge factor but I think the Boks will be well prepared for this final."

And Fleck admits England's marked improvement since their defeat to the Springboks has given him cause for concern.

He added: "They definitely have improved over the last couple of weeks. I'm slightly worried but all in all I think it will be an unbelievable occasion for both countries coming into this World Cup final."