Argentina gave up a half-time lead to lose to South Africa in Durban, but Rassie Erasmus knows his Springboks side must raise their game.
New Zealand and Australia suffered casualties in Sydney on Saturday that will force changes in the second Bledisloe Cup Test next weekend.
The daunting task of competing in a pool featuring New Zealand, South Africa and Italy is Namibia's reward for reaching the Rugby World Cup.
Argentina threatened a shock in the first half in Durban on Saturday, but South Africa eventually hit their stride and cantered to victory.
New Zealand turned on the style in the second half in Sydney after the Wallabies had defended superbly to lead at the break.
The Wallabies held their own against the All Blacks for 40 minutes, but Michael Cheika and Michael Hooper were frustrated by what came next.
For 35 minutes Australia looked a word-class rugby team. For 35 minutes Australia kept New Zealand scoreless. And then the two Smiths, Ben and Aaron, combined...
Steve Hansen felt New Zealand experienced "a different type of explosion" in the Bledisloe Cup opener in Sydney.
The RFU's decision to charge Danny Cipriani with "conduct prejudicial to the interests of the game" has not gone down well with Gloucester.
The RFU has charged Danny Cipriani with "conduct prejudicial to the interests of the game" following his common assault conviction.