Sonny Bill Williams out with knee injury, putting his World Cup chances in jeopardy

Sonny Bill Williams will undergo knee surgery which has the potential to harm his chances of a third successive World Cup with the All Blacks.

The veteran midfield back is forecast to be sidelined for at least six weeks after an operation was scheduled for Friday to tidy up cartilage damaged in the Blues' win over the Stormers two weeks ago.

Williams, 33, suffered the damage while setting up a try, having come off the bench at Eden Park.

He missed Saturday's win over the NSW Waratahs and will play only a small part at best for the remainder of the Super Rugby season.

The injury-prone Williams has started twice this season and come off the bench three times.

He also missed a match to be in Christchurch to help the Muslim community in the wake of the March 15 mosque shootings.

It was a similar story last year when Williams played just five times for the Blues.

He went on to add five Tests to his total tally of 51.

While Williams is hig hly-rated by All Blacks coach Steve Hansen, the cross-code star's Test chances aren't helped by the depth on offer at inside centre.

Ryan Crotty, Ngani Laumape and Anton Lienert-Brown are all proven Test performers in that position.

Ma'a Nonu has shown signs of unearthing his best form on return to the Blues although, unlike the others, the veteran wasn't named in Hansen's initial squad named to gather next week to begin preparations for the Test season.

Blues coach Leon MacDonald described the arthroscopic surgery for Williams as minor but a "big blow" to his team.

He predicts Williams will bounce back quickly once fit to return.

"Whatever he puts his mind to, he makes happen," he said.

"This year he really wants to make the World Cup squad and be a part of that obviously, so he's driven to recover well from this injury and get back on the field."