Sonny Bill Williams blasts critics saying he's under pressure to make Rugby World Cup

Sonny Bill Williams has hit out at claims he's under pressure to keep his spot in the All Blacks for the Rugby World Cup.

The midfielder rarely uses Twitter to respond to media stories about him, but Williams was clearly fired up, saying those who say he's under pressure need to 'get their priorities right.'

Williams wrote that playing sport for a living can't be compared to those who are struggling to deal with far bigger problems.

"And for those that say I'm under pressure playing a game that I enjoy," Williams wrote. 

"Get your priorities right. Look at what's going on in the world.

"Starving children, the single mother raising 3 kids, the atrocities refugees are facing around the world, racism. This is what I call pressure."

Williams comment is reminiscent of a famous quote from legendary Australian cricketer and World War II pilot Keith Miller, who said  "Pressure is a Messerschmitt up your arse, playing cricket is not".

Media stories have claimed there was now more pressure than ever on Williams to prove he deserves to be one of the four midfielders heading to Japan.

Williams will play a preseason game for his province, Counties Manukau in Katikati on Saturday.

He will then play for the Steelers in their season opening game against Taranaki on August 10 in Pukekohe, on the same day as the rest of the All Blacks are playing the Wallabies in Perth.

Williams, who turns 34 on Saturday has had another season ravaged by injuries which has led to All Blacks coach, Steve Hansen wanting him to get more game time under his belt by playing provincial level, than he would get inside the All Blacks environment over the next two weeks.

In a second tweet posted by Williams late on Wednesday night, he took a swipe at how private conversations had been leaked to the media, however, he didn't reveal who or what he was referring to.

"I find it very interesting when so called "private" conversations end up in the media," he wrote, before using a quote from human rights activist Malcolm X.