'It's something I have to live with for the rest of my life' - Sonny Bill Williams' All Blacks regret

Cross code great Sonny Bill Williams has reflected on being the first All Black to be red-carded in 50 years during the British and Irish Lions tour in 2017.

Williams was sent from the field in Wellington for a crunching headshot on Lions tourist Anthony Watson. Referee Jerome Garces sent Williams off, making him the first All Black to be red carded in half a century of rugby.

It was a decision that cost the All Blacks dearly, potentially swinging the result in favour of Warren Gatland's British and Irish Lions and ultimately a drawn series.

Williams, who was interviewed as part of the Amazon documentary on the New Zealanders 2017 campaign, says it is 'It's something I have to live with for the rest of my life'. Amazon have been releasing snippets from the 'All or Nothing' documentary series recently on Youtube, in which the former Bulldogs stars reflected on one of biggest regrets of his career.

"It was just a blur you know. Probably like a nightmare I guess. For the ref to make such a dramatic call in a massive game like that you know. 50 years, that's a big call."

"Walking off they said you can sit on the sideline or go in the sheds. My first thought was I let the team down and I'll go inside the sheds. I put my head down and thought 'nah' and went over to the bench."

In an unorthodox move, head coach Steven Hansen opted to sub off a forward, Jerome Kaino, and replace him with centre Ngani Laumape.

"The toughest thing for me personally, was 'like man, I let down the team'," said an emotional Williams. 'Nah I didn't talk.'

"After the game, coach came to me straight away. That's what the All Black environment is, we're brothers. You got to pick your brother up when he's down. The boys rallied around me.

"It's something that for myself, I will have to live with for the rest of my life."