Wallabies coach Robbie Deans has admitted that he still has a couple of key selection decisions to make before he names his World Cup squad and revealed that form in the Tri-Nations will be crucial.

The clash with the Springboks in Durban this weekend is the last Test match before Deans unveils his final list of 30 players to represent Australia at the global showpiece in New Zealand, so players on the fringes will have one last opportunity to win favour with the Kiwi coach.

When asked whether performances this weekend will have an influence on who he decides to take with him to the land of his birth to challenge for the Webb Ellis Cup, Deans was unequivocal in his response.

"Oh without a doubt. It's not resolved ... we know them all pretty well by now but, when it comes down to the last couple of positions, they're quite key," he told AAP.

Wallabies prop Ben Alexander admitted that the atmosphere within the squad is quite tense as the players are well aware that their performance this weekend could well determine whether or not they will be going to the World Cup.

"Everyone's trying to keep pretty relaxed but at training there's a definite edge. We've got some really, really good players who aren't getting a run at the moment so blokes that don't perform on Saturdays are going to find themselves not there next Saturday," he said.

There are also a number of high-profile Australian players currently on the comeback trail from serious injuries and who will be hopeful of being included in Deans' final World Cup squad.

Drew Mitchell (ankle), Wycliff Palu (knee), James Slipper (ankle), Tatafu Polota-Nau (knee) and Benn Robinson (knee) are all likely to make playing returns for the Australian Barbarians against Canada on the weekend after the World Cup squad is announced.

Deans is assuming that all of them will be fit in time for the World Cup, but he is not taking any chances and will be doing his best to monitor their progress while he is in South Africa.

He explained: "We're maintaining contact with them to make sure they use their Blackberry playbooks to record everything they do and they're sending clips of those across.

"We'll have some decisions to make, but we're just making sure that we're fully armed. We're getting footage, we're getting GPS numbers, so we're seeing what work they're doing and we're also monitoring their state so that we're fully informed and, between their status and our status, we'll make a decision," he said.