If he can prove he is reliable at throwing in to the lineouts, this could be a big break for former NZ Under-20s hooker Harris, as the All Blacks selectors continue to struggle to find back-ups for injury-prone Keven Mealamu and Dane Coles.
Certainly with his speed around the park and scrummaging ability, Harris is right in the frame and last year spent a few days in training with the All Blacks.
Schwalger is joined in the forwards by Ross Filipo, who gets his first start for the year.
Nick Crosswell and Sam Cane (Bay of Plenty) will be the starting flankers, with Liam Messam moving to No8 and Augustine Pulu at halfback.
Last week's centurion, Tanerau Latimer, is out with an Achilles strain but the Chiefs lose nothing with All Blacks flanker Cane busting to make an impression with the England series looming in June.
Tevita Koloamatangi comes on to the bench and is joined by halfback Brad Weber and veteran Dwayne Sweeney, who has re-joined the Chiefs after two years playing in Japan. James Lowe returns from a knee injury to take a place on the bench.
Bay of Plenty tighthead prop Josh Hohneck has had limited game time but has impressed with his scrummaging when he has been on the pitch. He will be on the bench again tomorrow.
Chiefs' head coach Dave Rennie says the Anzac Day fixture means so much to everyone involved in the match.
"It is special to be playing a match against an Australian team on Anzac Day. It is a hugely important day for our two countries."
Team update
Injuries: Liam Squire, concussion; Ben Afeaki, concussion; Kane Thompson, hamstring; Tanerau Latimer, Achilles; Tawera Kerr-Barlow, concussion; Charlie Ngatai, calf; Mils Muliaina, elbow (out for season); Robbie Fruean, heart; Robbie Robinson, hip (out for season); Aaron Cruden, thumb.
Suspension: Mike Fitzgerald.
Chiefs team to face the Brumbies at Canberra Stadium, tonight, 7.40pm kick-off:
1 Pauliasi Manu, 2 Mahonri Schwalger, 3 Ben Tameifuna, 4 Ross Filipo, 5 Brodie Retallick, 6 Nick Crosswell, 7 Sam Cane (Bay of Plenty), 8 Liam Messam (c), 9 Augustine Pulu, 10 Gareth Anscombe, 11 Asaeli Tikoirotuma, 12 Bundee Aki, 13 Andrew Horrell, 14 Tim Nanai-Williams, 15 Tom Marshall, 16 Nathan Harris (Bay of Plenty), 17. Jamie Mackintosh, 18 Josh Hohneck (Bay of Plenty), 19 Matt Symons, 20. Tevita Koloamatangi, 21 Brad Weber, 22 Dwayne Sweeney, 23 James Lowe.
Keep up with the game here:
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