The Springboks expect a more physical approach from the Wallabies when the two sides meet in their third Tri-Nations encounter in Bloemfontein on Saturday.

A loss for the Springboks would result in the team finishing bottom of the 2010 Tri-Nations log while a win would result in the final positions only being decided after the last match between the Wallabies and the All Blacks in Sydney next Saturday.

"We expect them to be more direct if one looks at their selection changes," said Springbok assistant coach Dick Muir on Thursday about the Wallabies and added that the visitors would probably "muscle it up and be more physical."

Fellow assistant coach Gary Gold pointed to the strengthening of the Wallabies' lineout, a more experienced pack and also that the changes probably made provision for more players with experience of playing at altitude.

"What's important is to build on last weekend's win," said Gold, who added that consistency of performance was important to the Boks.

The Springboks have now conceded four tries in two successive home Tests, and Gold said it was necessary to identify whether the defence system had let them down or whether it had been due to individual error.

Australia, with a better platform by their forwards, could be lethal on attack - and their scrumhalf Will Genia, flyhalf Quade Cooper and centre Matt Giteau needed careful watching.

To this end, Gold said relaxing the vigil on any one of the three could be fatal.

The Springboks played a rather expansive game last Saturday and it's expected they will play tighter this weekend, with a little more structured and be vastly better on defence.

"Performance is what we're working for and our ultimate goal is the World Cup," emphasised Muir.

The scrums and lineouts, with some exceptions, have been solid and should provide the basic platform even against a better, stronger and more experienced Wallaby pack which will face them on Saturday.

The Boks believe in their game plan built on the high ball and a good chase.

They will take it out wide when the occasion arises but this is a must-win Test (as all Tests should be). The winner takes the Mandela Challenge Plate currently held by South Africa and the losers run the risk of being wooden-spoonists.

It could go either way. However, this is not yet a classy Wallabies team, and the match is at altitude. The Boks should win, but it is hoped they will win well and put up that performance referred to by Muir.