Joe Schmidt has been called up to help prepare the All Blacks for Saturday's first test against his former charges Ireland at Eden Park after Ian Foster and two of his assistant coaches tested positive for Covid-19.
Schmidt coached the Irish for six years from 2013 and his reign included Ireland's first two wins over the All Blacks.
"Joe will come in for Tuesday and Thursday's training this week, and we're really grateful to have his help," Foster said in a statement.
"We've planned for this kind of disruption and we've got back-up plans and people on standby. Joe was one of those people we could call on.
"I've got every confidence in our coaching group and in our senior leaders who are all stepping up in what's a massive test for us."
Foster, John Plumtree and Scott McLeod are isolating at home after positive tests for Covid-19, which has also forced centres David Havili and Jack Goodhue out of the squad camp in Auckland.
Their Crusaders team-mate Braydon Ennor was called into the squad as midfield cover on Monday.
Ireland have also had a Covid-19 case in their squad with Australia-born outside back Mack Hansen forced into isolation.
Niall Scannell has been called into the touring squad as cover after hooker Rob Herring and lock Iain Henderson picked up knocks in training.
Before Saturday's opening test Ireland will play the Māori All Blacks in Hamilton on Wednesday in the first of two tour matches they will play in addition to three internationals.
The Māori All Blacks team for the match was named on Monday with test regulars Brad Weber and TJ Perenara sharing both scrum-half duties and the captaincy, the latter off the bench.