Sam Whitelock will lead the All Blacks for the first time after Kieran Read succumbed to a troublesome hip flexor issue that has plagued him for the past two weeks.
In better news, Rieko Ioane has made a surprise recovery.
Read picked up the knock against France in Paris, leaving the field early in the second half and battling since. He pushed through the pain barrier last week in Edinburgh, but this week has proved a step too far.
Read struggled to walk earlier this week, and was worryingly absent from training altogether today. Suggestions are the concern may have spread to his back.
Losing his experience, after 12 straight tests and 109 in total, is a blow to a team now stripped of seven genuine starters; many of them senior figures.
Without Read, Welsh fans may dare to dream of a first victory over the All Blacks since 1953.
On the flipside, it will be a special day in the Whitelock household with Canterbury captain Luke starting at No 8, in his first test since 2013, and Sam chosen to lead the team ahead of Beauden Barrett and Sam Cane after assuming the Crusaders captaincy and helping guide them to the Super Rugby title this season.
Sam Whitelock, the 29-year-old, 95-test veteran, will be the All Blacks' fourth captain on this tour and the 69th in tests. After Luke led the mid-week team, the Whitelocks join Wellington's Harry and Marcus Nicholls (from the 1920s) as the only set of brothers to have captained the All Blacks.
The other big news is the miraculous recovery of Ioane. Last week All Blacks coach Steve Hansen ruled the star finisher out of this test due to a rotator cuff injury to his right shoulder.
At the time, after the tense victory over Scotland at Murrayfield, Hansen said Ioane would only stay on to attend next week's World Rugby awards in Monaco, where he is nominated for breakthrough and player of the year.
Seta Tamanivalu looked set for his first test in 15 months after training in the starting backline on the left wing on Tuesday. But, two days later, to the major surprise of most observers, Ioane was back.
The 20-year-old still appeared to be carrying his shoulder somewhat but he pushed Tamanivalu out and will now take his place in the No 11 jersey.
It would seem he is a risk of sorts, but his pace and power provides a boost, one that may also catch the Welsh offguard given the original prognosis.
Patrick Tuipulotu's promotion to replace injured lock Luke Romano is also something of a full circle story. At this same stage last year Tuipulotu left the team in Paris to return home for "personal reasons" which later transpired to be a failed doping test.
Tuipulotu was, of course, eventually cleared by his B sample. In what will be his 16th test and fifth start, he now has the chance to further his case and finish 2017 on a much more memorable note than last year.
His selection over Scott Barrett is reward for a strong starting performance in the mid-week win over the French XV in Lyon, and suggests the All Blacks feel they need more physicality from their pack this week.
The other starting change sees Liam Squire return at blindside, pushing Vaea Fifita out of the squad.
No shortage of intrigue, then.
"Whilst it's disappointing to not have 'Reado' available, it's a great opportunity to further grow the leadership of the team and, in this case, Sam Whitelock gets the opportunity to captain the side. On behalf of the team, we'd like to congratulate him on this special honour," Hansen said.
"With his brother Luke captaining the All Blacks against the French XV, it will create a unique, All Blacks family history, and one which their family can be proud of.
"There's been a real energy and buzz in the team this week as we prepare for the test against Wales. The group has worked hard on its preparation, we've asked them to go bone deep and they're looking to deliver a performance we can all be proud of.
"It's always a pleasure to play in stadiums like the Millennium. We experienced a magnificent atmosphere last week up in Murrayfield and looking forward to a full house on Saturday. The Welsh are well known for their singing and that, in itself, creates something special. As always, we have been treated incredibly well here in Cardiff and have thoroughly enjoyed our week."
All Blacks team:
Damian McKenzie, Waisake Naholo, Ryan Crotty, Sonny Bill Williams, Rieko Ioane, Beauden Barrett, Aaron Smith, Luke Whitelock, Sam Cane, Liam Squire, Sam Whitelock, Patrick Tuipulotu, Nepo Laulala, Codie Taylor, Kane Hames
Reserves: Nathan Harris, Wyatt Crockett, Ofa Tu'ungafasi, Scott Barrett, Matt Todd, TJ Perenara, Lima Sopoaga, Anton Lienert-Brown