David Wojcinski was dropped and the Cats must also do without experienced midfielder Glenn Kilpatrick, who tore his hamstring against Fremantle.
An injury cloud hangs over Aaron Lord, who didn't train last night.
But the Cats welcome back defender Brenton Sanderson from a calf injury and Josh Hunt, who has been recalled after a week in the VFL.
Kelly, 18, is the sixth first-game player to make a senior debut this year for Geelong, following Gary Ablett, James Bartel, David Johnson, Paul Chambers and Jarad Rooke.
The former Calder Cannons player has been knocking on the door of senior selection for the past month after being among Geelong's best in its VFL side.
Geelong coach Mark Thompson said Kelly would replace Kilpatrick, who tore his hamstring midway through the first quarter of Geelong's win over Fremantle on Sunday.
Thompson said with Kilpatrick out, Geelong needed someone who could run hard and Kelly fitted the bill.
``He's a pacy midfielder and accumulator. He gets balls inside packs and he's a good runner and neat kick,'' he said.
Thompson's young Cats have handled the pressure of senior football well, but he said he didn't know how long that would last.
``It might last all year, it might go another three weeks,'' he said. ``When it happens we'll deal with it then but for now it's been working pretty well for us.
``We'll just go up there (Brisbane) and try our best and not be verwhelmed by them and play without fear.''
Brisbane's powerfully-built centre half-forward Jonathan Brown was doubtful early in week with an ankle injury but has been named in the team.
The Lions will be without only star Jason Akermanis after his suspension this week for kneeing, but have included premiership trio Alastair Lynch, Darryl White and Beau McDonald, and Des Headland. Jamie Charman, Craig Bolton and Ashley McGrath were axed after the Lions' shock loss to West Coast.
Geelong ruckman Peter Street, who injured his shoulder in a practice match against the Western Bulldogs in February, has been named in Geelong's VFL side to take on the Northern Bullants at Skilled Stadium on Sunday.
Former Geelong Falcon Matt Maguire will make his AFL debut for St Kilda tonight. Maguire, 18, played a Wizard Cup game earlier this year.