Ian Foster credits Argentina for adding to Rugby Championship's competitiveness

All Blacks head coach Ian Foster credited Argentina for the increased competitiveness in the ongoing Rugby Championship tournament.

Argentina have shocked both Australia and New Zealand in the second and third rounds of the competition with a 48-17 and a 25-18 wins respectively.

The results also meant all four teams in the competition are in the race to win the title heading into the final two rounds with New Zealand leading with 10 points while Argentina, South Africa and Australia have nine apiece.

"It's a very even competition, so that's probably where our eyes are firmly at the moment," said Foster.

"It is definitely unusual, but it's a sign that Argentina are certainly growing as a team, all their squad is now based in the Northern Hemisphere so they've been playing a lot of high competition games in the last couple of years.

"They've certainly reaped the rewards of that."

Ardie Savea will miss the key Rugby Championship clash with the Wallabies in Melbourne because of the birth of his third child and Foster was supportive of the decision.

"He's a key leader, a key player, but I'm massively supportive of the decision," he added.

"If you look at the last two or three years, where players have had to make some pretty tough choices with families, it's great to be able to support him and (his wife) and their family."