SBW to Guildford: 'Head up son'

Zac Guildford and Sonny Bill Williams wrestle during training for the Rugby World Cup. Photo / AP

Sonny Bill Williams has expressed his support for fellow All Black Zac Guildford.

Williams, currently on holiday in Brisbane, tweeted his support for Guildford, whose All Black career is in jeopardy after his drunken rampage in Rarotonga.

"Thinking of my boy Zac Guildford in these tough times," tweeted Williams. "Head up son."

After a string of embarrassing alcohol-related incidents during his early career, Williams converted to Islam and no longer drinks alcohol.