Mata'afa (25) gets a start after Hisa Sasagi (hamstring) and Donald Brighouse (strained rib cartilage) were ruled out with injury.
Sasagi's hamstring injury is likely to sideline him for three or four weeks.
Otago assistant coach Phil Young said Mata'afa's selection was a reward for his efforts with the development team and would provide plenty of go-forward with the ball around the fringes.
''He's got a good read on the game, but his main attribute is his ball-carrying,'' Young said.
''For a big man, he's got good ball skills and he's good in the set pieces.
''It will be a real test for him on Wednesday at this level, but we've got full confidence in him that he will come pretty good.''
The injury toll among the propping ranks also opens the door for Harbour front-rower George Bower to make his debut off the bench.
Bower had been asked to put on weight at the start of the season, and had put in the work to bulk up, Young said.
''He's been working hard, and he's put on seven or eight kilograms, which is really good for a front-rower.
''He's a fit man and very mobile.''
New Zealand under-20 lock Josh Dickson may also feature off the bench in what would be his first-class debut for for the province.
The loose forwards continue to rotate, as the Otago officials manage their stocks before the Ranfurly Shield challenge against Hawkes Bay in Napier on Sunday.
Lee Allan slots into the blindside flanker role, replacing TJ Ioane, and Hugh Blake gets a start for the rested James Lentjes.
''TJ's a wee bit banged up so, hopefully, he'll recover quickly and James Lentjes has had a lot of game time and a lot of minutes, so we're resting him as well.
''There's a lot of competition in the loose forward department and we've got a good loose trio on Wednesday night.''
Matt Faddes starts on the right wing in place of Marshall Suckling, and Josh Renton returns at halfback for Nick Ealey, but the rest of the backs get another chance to run together.
''They're starting to get some combinations together now - we're pretty pleased with how the backs have been playing as well.''
The news on lock Joe Latta's knee is better than first expected after he left the field in the Canterbury game with what appeared to be a reasonably serious injury.
Young said the Zingari-Richmond lock had recovered ''pretty well'' and should be available for selection for the Hawkes Bay clash.
Northland has made just one change to the side which toppled Hawkes Bay 23-21 on Friday but it could be a vital one.
Impressive winger Jone Macilai has recovered from an ankle injury sustained against Canterbury and returns to his spot on the left wing.
Otago v Northland
Dunedin, tomorrow, 7.35pm
Otago: Trent Renata, Matt Faddes, Jayden Spence, Teihorangi Walden, Fa'asiu Fuatai, Hayden Parker, Josh Renton, Charlie O'Connell (c), Hugh Blake, Lee Allan, Tom Franklin, Jackson Hemopo, Michael Mata'afa, Liam Coltman, Aki Seiuli. Reserves: Sam Anderson-Heather, George Bower, Josh Dickson, Naulia Dawai, Nick Ealey, Peter Breen, Tony Ensor.
Northland: Mathew Wright, Whiria Meltzer, Brook Gilmore, Troy Gilbert, Jone Macilai, Dan Hawkins, Tane Takulua, Cam Eyre (c), Jack Ram, Dan Pryor, Tom Murday, Shane Neville, Namatahi Waa, Matthew Moulds, Ross Wright. Reserves: Howard Sililoto, WillGriff John, Michael Stolberg, Kara Pryor, Kurt Davies, Latiume Fosita, Warren Dunn.
