Zak Hardaker will switch to the wing to cover for the loss of Ryan Hall after coach Wayne Bennett ruled out bringing anyone else into his Great Britain squad.
The Wigan full-back has played at right centre for the first two Tests, but has been switched to the left wing after Hall was ruled out with a knee injury.
Bennett had only included two wingers in his 24-man squad.
Meanwhile, Wigan centre Oliver Gildart will return to the UK tomorrow to continue his treatment for a dislocated shoulder suffered in the defeat to Tonga.
Sydney Roosters winger Hall is also departing. The Lions management have opted not to draft in any replacements.
Bennett said: "We have every faith in the ability of the players within our squad to get the job done.
"It is disappointing for Ryan and Oliver that they have had to leave the tour through injury."
St Helens prop Luke Thompson, though, returned to training today as he recovers from a rib injury suffered in the opening weekend.
He is in the provisional 21-man squad for Saturday's Test in Christchurch with Warrington forward Jack Hughes - a double-winner with Wigan in 2013 - named in the side at centre.
The rest of the side is settled from the 12-8 loss to Michael Maguire's Kiwis, meaning there is still no place for George Williams.