The back row has also been reconfigured, with Bay of Plenty youngster Sam Cane promoted back into the starting line-up. He will twin with Tanerau Latimer, who will wear the No 6 jersey.
"We'll mix it up a little, we'll play a little bit of left and right and we've got another No 7 on the bench in Scott Waldrom, so we've got a few options," Rennie said.
Liam Messam shifts to the back of the scrum after playing impressively on the blindside in the previous fortnight. Kane Thompson moves to the bench.
"Liam's been a massive influence in both our wins," Rennie said. "We're really pleased with him. He's done a lot of graft and played very much a tight loose-forward role."
The other change to the Chiefs line-up is the inclusion of Jackson Willison at centre, with Richard Kahui taking over from Asaeli Tikoirotuma - who is on bereavement leave - on the wing.
"Jackson was in great form during the pre-season and did a hammy leading into game one, so he deserves a crack. Obviously Richard has a fair bit of experience on the wing."
The Chiefs travel to Mt Maunganui on a high after back-to-back wins against traditional heavyweights the Blues and Crusaders.
The Jake White-coached Brumbies were lucky to leave Canberra with a win against the Cheetahs, but remain unbeaten after two matches.
They are not a team full of big names, but they look strong in the front-row. Ben Alexander and hooker Stephen Moore have 102 test caps between them, while Dan Palmer is considered one of the most technically proficient scrummagers in the country.
CHIEFS
Hamilton, 7.35pm tomorrow
Robbie Robinson
Richard Kahui
Jackson Willison
Sonny Bill Williams
Tim Nanai-Williams
Aaron Cruden
T. Kerr-Barlow
Liam Messam
Sam Cane
Tanerau Latimer
Brodie Retallick
Craig Clarke
Ben Tameifuna
Mahonri Schwalger
Arizona Taumalolo
Chiefs: Marcel Cummings-Toone, Josh Hohneck, Kane Thompson, Scott Waldrom, Augustine Pulu, Andrew Horrell, Maritino Nemani.
BRUMBIES
Jesse Mogg
Pat McCabe
Andrew Smith
Joe Tomane
Henry Speight
C. Lealiifano
Nic White
Ben Mowen (c)
Michael Hooper
Scott Fardy
Peter Kimlin
Power/Carter
Dan Palmer
Stephen Moore
Ben Alexander
Brumbies: Anthony Hegarty, Ruaidhri Murphy, Sam Carter, Ita Vaea, Ian Prior, Zack Holmes, Cam Crawford.