The senior trio, who share 251 caps between them, came off the bench last weekend and turned the game as Wales hit back from 17-9 down to open their World Cup with a 42-17 win over Canada.

And Jenkins backed them to inspire Wales again on Saturday in a match with a huge amount at stake.

Victory would give them every chance of finishing top of Pool B and earning a quarter-final against struggling England rather than the dangerous South Africans.

Jenkins said: “We have brought in three players who showed last weekend what experienced heads can do to a performance.

“They picked up the game by the scruff of the neck against Canada and were able to fashion a victory for us.

“This is the most important match we have played during my tenure and probably the most important game a Welsh side has played for a long time.

“We must be focused, cold, hard and determined. This squad has those qualities, together with the self-belief, talent and ability to achieve a significant victory.”

Of the returning senior trio, Jenkins’ fly-half selection was the most significant.

Jones has endured a turbulent year, suffering a huge amount of criticism as he captained Wales through a disappointing Six Nations campaign. The emergence of Hook only served to heighten the pressure.

But Jones dealt with even the fiercest bares politely – just one reason he is nicknamed ’Smiler’ – and last weekend emerged as Wales’ hero once again.

Jenkins took the opportunity today to remind those critics – some of whom he accused of attempting to “destroy” and “discredit” him – that Jones still has a major role to play for Wales.

“Stephen has had to deal with a lot of horrible stuff. He has dealt with it because of the person he is,” said Jenkins.

“Stephen has proven to them and everyone in Wales he has still got a fantastic contribution to make to the Welsh team.

“Players will come in and out of form. When that happens we react with selection.

“Stephen is particularly energised at the moment and he is really excited about this World Cup. I think he is the right man for the job on Saturday.

“He is a great outside half and a great player.

“I think James Hook will be another great player. Between the two of them we have the model of a perfect outside half.

“But where Steve is at the moment, James can’t be.

“Steve has developed fantastic experience and James can learn so much off that.”

Hook will be asked to cause Australia problems off the bench, just as he did to such great effect in the 29-29 draw last November.

Thomas is also chomping at the bit after being denied a start last weekend and he returns to the starting XV at full-back in place of Kevin Morgan.

“Gareth is a proud man. He supported my selection last week but he was disappointed he wasn’t playing,” Jenkins said. “When he and Stephen did come on that field, they brought charisma and confidence and the players responded to that.

“I am sure both of them will do that for us on Saturday. We want a big game from Alfie, we want a big game from Stephen.

“This is probably the biggest game in the tournament as far as we are concerned. Our top players need to play their best rugby on Saturday.”

And key to that will be Charvis, who impressed against the Wallabies on Wales’ summer tour and has edged out Alix Popham to start at blindside flanker, with Jonathan Thomas switched to number eight.

Wales head into the match buoyed by home advantage – “it can be worth 15% to us” and their recent performances against Australia in Cardiff, winning in 2005 and drawing last November.

“We have gone through practically every emotion possible in our last four meetings with them. We have beaten them and drawn with them in Cardiff, lost narrowly in Sydney and been put to the sword in Brisbane,” said Jenkins.

“But World Cup rugby pays no respect to history or to emotion. We know Australia have the finest pedigree of any nation at the World Cup.

“We respect them as an outstanding rugby nation – but we do not fear them and on Saturday we have a chance to prove that.”