Chiefs coach Clayton McMillan confirmed he hadn't had any discussions with the All Blacks around giving Vaa'i reps on the side of the scrum and that with Mitch Brown, Simon Parker, Samipeni Finau and Luke Jacobson all unavailable, it left him with few other options.
"I've almost been forced into it," McMillan said. "Having said that, he's a very athletic individual and I've got no concerns that he'll do anything but a good job...it's going to provide us with another option – assuming it goes well.
"The other part of it is we've got five really good locks and we haven't had to opportunity to play them all, so we need to get some minutes into them knowing that we've got a few big weeks ahead of us. This is another way we can get them all out on the park."
With Vaa'i shifting to flanker, Josh Lord comes into the starting side for the first time this season, after Laghlan McWhannell opening the year alongside Brodie Retallick in the locking department.
In their round one win over the Highlanders, McWhannell was among the best players on the pitch but because McMillan wanted to get all of his locks some time early this season, the 23-year-old was the one to miss out this weekend, with Naitoa Ah Kuoi providing back up on the bench.
"The postponement of the Moana Pasifika game was unfortunate because it would've given us an opportunity to give some of those guys a run," McMillan said.
"The guys that are playing this week, their job is to do such a good job that it makes it hard for Laghlan to get back in there – which they'd have to perform pretty well to do that."
Elsewhere in the squad, Anton Lienert-Brown is set to make his first appearance of the season in a bench role as the side take a conservative approach to bringing him back into the game after he sustained a shoulder injury on the All Blacks' end of year tour in 2021.
Co-captain Brad Weber returns to the starting lineup to lead the side out in his 100th Super Rugby appearance, while fellow All Black Samisoni Taukei'aho will also be in the run-on squad after starting the year on the bench.
Blues v Chiefs
Eden Park, Saturday March 5, 4.35pm.
Blues: Stephen Perofeta, Mark Telea, Rieko Ioane, Roger Tuivasa-Sheck, Caleb Clarke, Harry Plummer, Finlay Christie, Hoskins Sotutu, Dalton Papalii, Tom Robinson, Josh Goodhue, Luke Romano, Nepo Laulala, Kurt Eklund, Alex Hodgman.
Reserves: Ricky Riccitelli, Ofa Tuungafasi, Marcel Renata, Sam Darry, Adrian Choat, Sam Nock, Beauden Barrett/Zarn Sullivan, AJ Lam.
Chiefs: Chase Tiatia, Shaun Stevenson, Alex Nankivell, Quinn Tupaea, Etene Nanai-Seturo, Josh Ioane, Brad Weber, Pita Gus Sowakula, Sam Cane, Tupou Vaa'i, Brodie Retallick, Josh Lord, Sione Mafileo, Samisoni Taukei'aho, Aidan Ross.
Reserves: Bradley Slater, Ollie Norris, Angus Ta'avao, Naitoa Ah Kuoi, Kaylum Boshier, Xavier Roe, Bryn Gatland, Anton Lienert-Brown.