The Elementary Coaching 101 manual pushes the point that you never change a winning team. But in the case of Michael Cheika, the Wallabies and with a World Cup hovering, it is understandable he has made sweeping changes to the starting XV for this weekend's Test with Argentina in Mendoza.

Some have been forced through injury; others by the need to give fringe candidates a try, especially as they excelled in the final stages of the win over the Springboks in Brisbane. Cheika is approaching the Rugby Championship as a selection guide for the World Cup, and now is the time to experiment, to tinker with different combinations, and to properly work out whether some players are actually up to it.

The simple fact about the Brisbane victory is that the reserves bench got the Wallabies out of the mire; and so a number of them deserve their chance against the Pumas.

The scrum improved immeasurably in the second half, and that had a lot to do with the anchor provided by Reds tighthead Greg Holmes, who this week has been elevated to a starting spot for the first time since 2007. It is a worthy selection, enhanced by the fact that Holmes will be accompanying his Reds front-rower James Slipper. They understand each other's game, and so should provide solid resistance - which is imperative against the Pumas pack.

Greg Holmes has been given the chance to anchor the Wallabies scrum © Getty Images

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Scott Higginbotham failed to make the Wallabies No 8 position his against South Africa, as he often drifted out of the play, and so it is now Ben McCalman's turn. McCalman is a honest trooper, and rarely has a bad Test match. It is crucial that the Wallabies certify before the World Cup who their No 8 is - as this is a real problem area for Australian rugby.

Alternating the David Pocock-Michael Hooper roles is also good man management, and there is no doubt we will again see both of them on the field at some time during this weekend's Test.

A midfield change has been forced because Will Genia and Matt Giteau are both injured. But even if Genia was fit, he would have still struggled to make the starting XV as Nick Phipps was of a superior quality when he came on during the second half.

Phipps appeared to lose his way in the latter stages of the Super Rugby season, too often playing the 'Angry Ant' role in agitating referees, opponents and teammates. He appeared distracted and his standards slipped, especially his passing. But against the Springboks, he regained control of his game, and his passing in particular improved immeasurably. Having Bernard Foley beside him will help, while Matt Toomua is the natural choice for Giteau.

Hopefully Foley and Toomua will alternate between No 10 and 12, as I believe Toomua must spend some time at the playmaker role. He of all the No.10 candidates is the most assured.

And Cheika is giving all wing candidates a chance. Last week: Rob Horne. This week: Joe Tomane. And on the bench, Dean Mumm and Nic White will get their chances.

Again all understandable!