Wells will be on the bench with Areta Lama starting first-five and his Kaierau team mate Josh Edwards earning a promotion to No9, with Lindsay Horrocks also dropping back.
"Josh gives us a lot with Areta, they have a good understanding and working relationship," said coach Karl Hoskin.
He still expected Ulukuta and Lindsay Horrocks to be impact players in the last quarter.
While Rowe was "gutted" to stand aside and despite the constant changes meaning so many guys are playing in different combinations every week, Hoskin said there is no deep sports psychology tactic that will help.
In such a tight competition this year, they know every chance must be snatched if they are to reverse two straight losses.
"It was not ideal to have four flankers down from the first game, then to go to Westport and be left with 15 players fit for the final 45 minutes.
"Training hasn't been any less intense, and no one's dropped their head.
"We are so close one point and four points short we have the opportunities and they're falling short."
To that end, much will depend on goalkicking and here the spotlight falls on teenager Zyon Hekenui, who makes the starting lineup on the wing despite a full club season at fullback.
"We've played him at wing a few times in the preseason games, he has pace and is still a potent threat there," said Hoskin.
With only two tries to show from Wanganui's opening 160 minutes, in a Heartland competition where eight of the 12 games so far have been decided by under seven points, expect another nerve wracking affair at Cooks Gardens tomorrow.
"It's going to be a very confrontational game, a lot of hard hitting going on," said Hoskin.
"[South Canterbury's] got some big boys so it's just about us getting in there and getting points every opportunity we can, because they'll get up a big head of steam."
The visitors were unsuccessful in their first North Island excursion, beaten 21-17 by Thames Valley, but rebounded last Saturday to beat powerful neighbours North Otago 21-15, ironically the first time they'd won the local derby in Timaru since 1997.
Prop Timaru Tafa played his 50th game last week.
The curtain-raiser will be Wanganui Development XV taking on Wairarapa Bush B in an RDO Cup match, at 12.45pm.
Wanganui vs South CanterburyKickoff: 2.30pm.
Referee: Sheldon Eden-Whaitiri (Auckland).
Steelform Wanganui Asalemo Malo, Zyon Hekenui, Jason Hemara, Pehira Huwyler, Robert Hughes, Areta Lama, Josh Edwards, Jason Hughes, Doug Horrocks, Andrew Evans, Nick Cranston, Sonny Woodmass, Shaun McDonough, Roman Tutauha, Vaan Rauhina (capt).
Reserves Backs: Lindsay Horrocks, Soonalote Tauailoto, Tom Wells. Forwards: Karl Parker, Kim McNaught, Lasa Ulukuta, Fa'alafi Vave.
Trust Aorangi South Canterbury Liam Edwards, Tenari Saumani, George Folua, Aporosa Tabulawaki, Tristram Johnston, Sam Vaevae, Scott Norton, Kali Latu, Nick Strachan, Hayden Mitchell, Luke Brice, Andrew Scarlett, Timaru Tafa, Nathan Tubb, Matt Fetu.
Reserves Backs: Theo Davidson, Josh McAtamney, Kurt Rooney. Forwards: Jonny Andrews, Aifala Taelega, Timothy Penitani, Joeli Kotobolavu.
RDO CupKickoff: 12.45pm
Referee: Vincent Ringrose (Wellington).
Wanganui Development XV to play Wairarapa-Bush B
Moli Sagapolutele, Aaron Vadiga, Tremaine Gilbert, Sailosi Nagicu, Mohi Waihi, Jayden Matson, Tyler Rogers-Holden, Sanele Ah Chookoon, Brad Matthews, Sam Madams, Simon Hillis, TBC, Lucas Puts, Junior Tume, Kamipeli Latu.
Reserves Backs: Josaia Navitio, Lee Ashford, Grayson Tihema. Forwards: Robbie Lavin, John Small, Fraser Bryant, Jack Hodges.
