The Cats have decided to take no chances on Horlin-Smith, who has been taken out of the team because of groin soreness.
Fellow youngster Brad Hartman has been brought into the Cats' final 22, while Darcy Lang has been upgraded to the emergency list.
Horlin-Smith has averaged 16.5 disposals and kicked 13 goals in 18 games this season.
Jimmy Bartel and Jordan Murdoch are the other two inclusions in the Cats' side, while Jed Bews and Billie Smedts were both dropped.
St Kilda has also suffered a setback, with ex-Hawk Shane Savage being withdrawn from the team to face Richmond due to injury.
The Saints revealed on Friday afternoon that Savage had suffered a fractured arm at training which will rule him out for the rest of the season.
Sam Dunell has taken Savage's place in the 25-man squad which will be trimmed by three later on Friday.
