For the Chiefs, it is important; for the defending champions, it is must-win.
The Chiefs welcome back Brodie Retallick and Liam Messam after they were rested against the Lions, while Alex Bradley has got the nod over Kane Thompson for the No 8 jersey.
In the end, it was probably the fact that Mike Fitzgerald has undergone a procedure to have his nose re-straightened after breaking it against the Lions that saw the call go in Bradley's favour.
"That was a really close call," Rennie revealed. "It was one of the positions we haggled over during the week. In the end, we're starting Alex because Kane will cover both No 8 and lock."
One of the few selections forced on the Chiefs was Brendon Leonard at halfback. He has mixed the good with the not-so-good since his return from a hamstring injury, but Tawera Kerr-Barlow's illness makes Leonard's experience vital against the prodigious talents of Will Genia.
"We would have started Tawera this week, but he's crook," said Rennie. "He's had the flu. It's got to the stage where he'll work hard but have trouble breathing and vomit.
"We thought he was on the improve ... but it hasn't progressed quick enough."
The Reds made life difficult for the Crusaders last week but Rennie said that there were still chinks in their armour they would look to exploit.
"They're a good side. They've steeled their defence from where they were four or five weeks ago.
"Obviously Genia's a big part of their play and we need to be able to stifle his running and kicking game."
Reds prop Ben Daley will start in the front row. Daley missed the Reds' 15-11 loss to the Crusaders last weekend with a hamstring strain. He replaces Greg Holmes. Flanker Beau Robinson also returns from injury, which sees the out-of-form Radike Samo drop out of the squad.
Coach Ewen McKenzie said: "You can sense a huge lift in the confidence and intensity of our play following the return of a number of players and they will only continue to play better the more they get the opportunity to play alongside one another."
Reds v Chiefs
Brisbane, tomorrow, 6.10pm
Luke Morahan
Dom Shipperley
Anthony Fainga'a
Mike Harris
Digby Ioane
Ben Lucas
Will Genia
S. Higginbotham
Liam Gill
Jake Schatz
James Horwill (c)
Rob Simmons
James Slipper
James Hanson
Ben Daley
Reserves: Saia Fainga'a, Greg Holmes, Adam Wallace-Harrison, Beau Robinson, Eddie Quirk, Nick Frisby, Rod Davies.
Andrew Horrell
Lelia Masaga
Richard Kahui
Sonny Bill Williams
Asaeli Tikoirotuma
Aaron Cruden
Brendon Leonard
Alex Bradley
Tanerau Latimer
Liam Messam
Brodie Retallick
Craig Clarke (c)
Ben Tameifuna
Mahonri Schwalger
Arizona Taumalolo
Reserves: Hika Elliot, Toby Smith, Kane Thompson, Sam Cane, Augustine Pulu, Jackson Willison, Robbie Robinson.