Hamstring injury makes Sonny Bill Williams a doubtful starter in New Zealand's Rugby Championship opener

Blues centre Sonny Bill Williams has suffered another injury setback that puts him in doubt for the Rugby Championship opener against Argentina in Buenos Aires.

Williams already missed the most of the Super Rugby campaign for Blues with a knee injury but despite the setback he was named in the 39-man squad of the All Blacks for the first two games of the Championship.

Just when he was in line to return for his local side to prove his fitness to Steve Hansen, a hamstring injury that he suffered during the training has cast a huge doubt on his participation in the game against the Pumas.

The 33-year-old has played 51 Tests for the All Blacks since his debut in 2010 and was last seen during the November series clash against England at Twickenham Stadium.

Earlier, Hansen said Williams has proved enough to walk into the World Cup squad of New Zealand provided he proves his fitness.