Ben Smith hat-trick helps New Zealand beat Australia

A hat-trick from Ben Smith helped New Zealand beat Australia 47-29 in the opening match of the Rugby Championship in Sydney.

Aaron Cruden, Conrad Smith and captain Richie McCaw also crossed to make it a disappointing first match in charge for new Wallabies coach Ewen McKenzie.

The sides meet again in the second match next Saturday in Wellington.

South Africa thrashed Argentina 73-13 in Johannesburg, with nine tries, and fly-half Morne Steyn kicking 28 points.

Winger Smith became the first All Black to score a hat-trick of Test tries since Doug Howlett in 2005 as the world champions exploited Australia's poor defence to claim a bonus-point victory and their 100th Test win over their old rivals.

Smith scored the first of his three tries after just three minutes, before tries from Cruden, who finished with 20 points after kicking three conversions and three penalties, and McCaw put them in firm control.

Will Genia responded with a superb 60-metre try shortly before the interval after a Michael Hooper break. Christian Leali'ifano converted and Australia trailed 22-19.

But Cruden kicked the All Blacks further ahead at the break after the Wallabies were caught offside inside their own quarter.

Conrad Smith secured a New Zealand bonus point and Ben Smith went over for his second try soon before completing his hat-trick eight minutes from time.

Australia, who grabbed a consolation second try through James O'Connor late in the match, must win in Wellington and the third Test in Dunedin in October to win back the Bledisloe Cup.

Meanwhile, the Springboks' victory margin set a new record for the southern hemisphere international competition, which was expanded to include Argentina in 2012, beating their 53-8 win over Australia in 2008.

Following a penalty try, eight different scorers crossed the line for the home side.

JJ Engelbrecht, Adriaan Strauss, Willem Alberts, Jean de Villiers, Fourie du Preez, Bryan Habana, Duane Vermeulen and Bismarck du Plessis all scored before Argentina captain Felipe Contepomi touched down in the last minute.