Rugby Championship: 'Grumpy' Sonny Bill Williams doubtful for All Blacks as Ngani Laumape impresses coaches ahead of Argentina clash

Sonny Bill Williams is a serious doubt to play for the All Blacks against Argentina this weekend.

Williams, who has been struggling with injuries this year, is likely to miss the All Blacks' first test of the year against the Pumas in Buenos Aires.

The 33-year-old travelled with the side to Argentina as he recovers from a tight hamstring he suffered after playing for the Ponsonby club recently, but is unlikely to start this weekend.

Assistant coach Ian Foster, who admitted Williams was a bit cranky with him in training, didn't rule out the veteran midfielder but said he was doubtful that he would play.

"He's doubtful, but he is training really well," Foster said.

"He's grumpy with me for holding him back a bit today because he's ready to go. He's feeling really good, but we just got to make sure we get full strength back into that leg."

Williams' lack of fitness could open the door for Ngani Laumape, who will be out to prove he deserves to be on the plane to Japan come September.

The Hurricanes midfielder was dropped from last year's Rugby Championship squad before returning as injury cover where he made appearances against Australia and Argentina. He also played against Japan and Italy in the northern tour.

With the All Blacks' midfield being one of the most competitive positional areas as the side gears up for the World Cup, Laumape says he feels like he is getting better and has done what he needs to do to impress selectors.

"I'm just trying to get better every year," Laumape said. "Obviously there was stuff I needed to work on. Every week in Super I was trying to get better and better.

"I felt like I did what I needed to do."

Foster was also positive about Laumape's development, saying he was "outstanding" against Japan in Tokyo last year and was pleased with his desire to be more vocal on the field during the All Blacks' end of year tests.

"He brought a stronger voice, he organised better, he was happy to jump into first receiver," Foster said.

"And he also developed a kicking game. I think he kicked three times on the end of year tour and we scored three tries. So that's not a bad strike rate.

"He's making big shifts and putting his hand up. It's great."

The All Blacks take on Argentina on Sunday morning (NZT) in Buenos Aires.