Wellington - New Zealand's Barrett brothers have been rocked by a family tragedy ahead of the All Blacks' quarter-final showdown with Ireland, after their grandfather died unexpectedly.

A death notice in the New Zealand Herald announced the "sudden passing" of Edward Michael (Ted) Barrett, aged 78, on Sunday surrounded by family in the North Island district of Taranaki.

It described him as a cherished husband, loving father and "adored Grandad Ted of all his grandchildren and his great-grandchild".

The grandchildren include siblings Beauden, Scott and Jordie, who earlier this month became the first trio of brothers to play for the All Blacks at a Rugby World Cup in New Zealand's 63-0 win over Canada.

They are set to miss their grandfather's funeral in New Plymouth on Wednesday as the defending champions prepare for a crunch quarter-final against Ireland on Saturday.

The close-knit Barrett clan all hail from Taranaki, where the brothers' father, former Wellington Hurricanes forward Kevin, runs a dairy farm and raised eight children with wife Robyn, a talented former netballer and basketballer.