SBW a doubt for Pumas clash

Sonny Bill Williams is a doubt for New Zealand's Rugby Championship opener against Argentina due to a hamstring injury.

The Blues centre was this week named in the initial All Blacks squad for the clashes with the Pumas in Buenos Aires on July 20 and South Africa in Wellington a week later.

Williams may not be available to feature for the world champions, though, as he is suffering from a tight hamstring.

The 33-year-old missed much of the Super Rugby season after undergoing knee surgery.

Williams played 50 minutes in a club match for Ponsonby against Grammar TEC last week before suffering another fitness setback.

The powerful midfielder has been linked with a return to rugby league after the Rugby World Cup in Japan.