There are calls-ups for New Plymouth BHS lock cum loose forward Tom Florence, an original 2015 NZ Schools selection before injury, and Rotorua BHS halfback Te Ra Whata.
His First XV teammate Kaleb Trask will wear the No 10 jersey tomorrow, switching from fullback, while Danny Toala moves from the outside backs into centre and Hamilton BHS five-eighths Rameka Poihipi will slot into second five. Fortunately the bulk of the pack remains unscathed.
"Our first half performance (on Monday) was as good as you'll see at schoolboy level," says Martin. "The physicality we brought was perhaps a bit of a shock to the Australians. The second half we went off the boil in terms of our game management."
But he was very satisfied with the set-piece against a bigger Australian pack. It just needed some more tactical nous in the wet, which may be a factor tomorrow.
Having watched Fiji Schools twice in the last week, Martin knows set-piece will again be vital, as will tackling accuracy.
Leading the way in that facet should be Joe Johnston, the King's No 7 who is promoted from vice-captain to captain after McClutchie's elevation to NZ Schools. He doesn't feel the side will have to depart too much from the Barbarians' ideals if it gets wet tomorrow.
"As long as we front up, keep the ball in hand and squeeze up a bit, we'll be fine. But there are a lot of athletes in the Fiji team. They play a very fast, free game," says Johnston, who skippered the King's First XV in 2016.
He will play his rugby in his native Bay of Plenty next season, hence he appeared for the Chiefs Under 18s in July.
The Barbarians club and learning about its history and ethos have been a welcome eye-opener for Johnston.
"There's a great culture here but still very professional. The boys are proud to play for the Barbarians," he says. "We've had a talk about upholding the Barbarians' winning international streak, so hopefully we can do it against Fiji."
Despite the six changes, the Barbarians still look well equipped to handle the unstructured, physical Fijians.
The NZ Schools v Australian Schools follows at 2.55pm.
NZ Barbarians Schools: Jamie Spowart, Connor Garden-Bachop, Danny Toala, Rameka Poihipi, Niven Longopoa, Kaleb Trask, Folau Fakatava, Kaylum Boshier, Joe Johnston (c), Matene Ruawai, Cameron Suafoa, Naitoa Ah Kuoi, Tevita Mafileo, Ricky Jackson, Kianu Kereru-Symes; Reserves: Perry Karati, Sam Matenga, Sue Asomua, Tupou Vaai, Tom Florence, Te Ra Whata, AJ Lam, Hayze Perham
Fiji Schools: Team TBC