By Nick Mulvenney
SYDNEY (Reuters) - The Tri-Nations kicks off on Saturday when an inexperienced Australia host New Zealand in front of a 40,000 crowd at Sydney's Olympic Stadium but all eyes at will be on a much older prize -- the Bledisloe Cup.
The withdrawal from the Rugby Championship of world champions South Africa over player welfare concerns has left a rump competition to be played out over the next six weeks between the trans-Tasman Sea rivals and Argentina.
The All Blacks and Wallabies got a head start on the Pumas with two tests played in front of big crowds in New Zealand over the last month and the competitiveness of those matches has whetted the appetite for Saturday's contest.
A 16-16 draw in Wellington followed by a 27-7 All Blacks win in Auckland means the Bledisloe Cup series remains alive even if the Wallabies need to win the last two matches if they are to end New Zealand's 17-year grip on the trophy.
"We know it will be a massive effort from the Wallabies this week," All Blacks coach Ian Foster said on Thursday.
"It's a do or die for them and that's the way they will see it. The key thing for us is that we have to make it a do or die thing for us too."
New Wallabies coach Dave Rennie is still enjoying his honeymoon period but injury has ended any question of his phasing in the transition to a new generation of playmakers.
Matt Toomua and James O'Connor have both been ruled out for Saturday and so flyhalf Noah Lolesio and inside centre Irae Simone will make their test debuts.
Rennie will clearly be hoping his forwards can give them the platform they provided to Toomua and O'Connor with their aggressive display in Wellington.
"We've seen where we think we've created opportunities for ourselves," the New Zealander said on Thursday.
"There are little areas that we think we can get some joy."
Rennie will also be looking for a much lower missed tackle count than at Eden Park and a strategy that avoids kicking the ball to New Zealand's back three, especially young left winger Caleb Clarke.
Foster, also taking charge of his third test on Saturday, clearly believes he got his selection right at Eden Park and has made only three changes, one expected and two enforced, to his team.
Despite having dominated the Bledisloe Cup exchanges since 2003, the usual match scheduling means New Zealand have not actually secured the trophy on Australian soil since 2009.
"I think that will be a special achievement," Foster added.
"We have to make sure that we show our colours playing away from home and that we can lift our performance regardless of which country we're in."
(Reporting by Nick Mulvenney, editing by Christian Radnedge)