All Blacks ace Dan Carter could be sidelined for up to six weeks as his injury-blighted year suffered a further setback in their 29-15 win over the Springboks on Saturday. It\'s a further blow for the Rugby Championship leaders who have already lost captain Richie McCaw for at least four weeks. Carter, the world\'s leading points scorer, grimaced in pain as he went down in a shoulder charge by Springboks hardman Bismarck du Plessis in the 15th minute of the fiery fourth-round match. \"He\'s done an AC (joint) and they\'re usually four to six weeks,\" coach Steve Hansen said. Du Plessis, who was sent to the sin bin for the charge, was later automatically red-carded out of the game when he received a second yellow card for elbowing Liam Messam in the throat. The All Blacks had captain Kieran Read and centre Ma\'a Nonu yellow carded in the closing stages of the bruising battle between the top two sides in the world. It was only Carter\'s second start in the southern hemisphere championship since returning from a thigh injury. Earlier in the year, a broken hand kept him out of two of the three home Tests against France. New Zealand\'s second string fly-half Aaron Cruden is also injured and third-choice Beauden Barrett came on as Carter\'s replacement against the Springboks and had an immediate impact on the game. He produced a 55-metre burst that ended with a try to Brodie Retallick and extended the All Blacks lead in the match to 14-3 and they remained in command from there. Although the All Blacks have shown they have depth at fly-half, Carter is rated as the world\'s best with his all-round game -- accurate kicking, strong running and fearless defence. Hansen rates him as \"certainly the best (fly-half) in the history of the game\" although the 31-year-old has been injury-prone in recent years. He was denied a place in the 2011 World Cup final, won by the All Blacks 8-7 over France, because of a groin injury and was sidelined for part of last year\'s Rugby Championship series against Australia, Argentina and South Africa. Source: AFP