But encouragingly, Craig Newby got through his first contact training run yesterday, in a comeback from injury, increasing his chances of being available for the start of the competition.
Matenga, who has played lock and blindside flanker for his club side this season, will start in the No 7 jersey for Otago when it takes on Wellington at Porirua Park on Friday afternoon.
Otago coach Steve Martin said Matenga had some experience playing openside flanker at school and if he was a success, that coupled with his experience at blindside flanker, would bring someone into the squad who could play both sides of the scrum, which was "a huge advantage when naming a squad of 22".
Kaikorai forward Seko Qaraniqio would start at blindside flanker, adding height and athleticism to the Otago team, Martin said.
Other features of the team are Sean Romans starting at halfback ahead of Toby Morland, and Ben Smith getting his second straight start at fullback.
The side will be captained by hooker Jason MacDonald, taking over from No 8 Steven Setephano, who is injured.
There are seven changes from the side that started against Southland last Saturday.
Glen Horton is yet to sign a new contract with Otago, though negotiations continue.
Heriot loose forward Shaun Tauti was to start on the bench but would get a chance, Martin said.
The last player from Heriot to play for Otago was hooker Paul Smith, who played a couple of games in 1996.
The loose forwards have been hit hard by injury.
Setephano re-aggravated a calf injury against Southland and is not expected back for four weeks.
Newby has been struggling with a neck injury, while Eben Joubert has a broken finger.
Openside flanker Alando Soakai is to have a shoulder reconstruction and is out for the season.
Martin said Newby went well at training yesterday, and he hoped to have him available for the Southland game in Invercargill on August 2, the first game in the national competition.
Martin wants to start firming up with combinations on Friday night, and is seeking an improvement in defence.
Against Southland last week, Otago was quickly ahead 19-0 before conceding seven tries to lose 36-43.
The squad would do the return trip to the capital in one day, which Martin described as the "reality of professional rugby".
Players would not be available to play club rugby on Saturday.
The Otago Air New Zealand Cup squad is named on Sunday, and the team then goes into camp at Waikouaiti for three days.
The Wellington side is due to be named today.
It is coached by former Otago players Jamie Joseph and Andre Bell.
A Wellington XV lost to 13-5 Taranaki 5-13 last Friday.
Otago team
To play Wellington
Ben Smith, Karne Hesketh, Brett Mather, Aaron Bancroft (vice-captain), Lucky Mulipola, Daniel Bowden, Sean Romans, Paul Grant, Hoani Matenga, Seko Qaraniqio, Tom Donnelly, Ross Kennedy, Jed Vercoe, Jason MacDonald (captain), Jeremy Aldworth.
Reserves: Peter Mirrielees, Ben Nolan, Uili Koloofai, Shaun Tauti, Toby Morland, Chris Noakes, Casey Stone, Dan Snee, Carl Anderson.
