It's welcome news for the Power which gains one half of its two key backmen, with Jackson Trengove still at least one week away.
"It's significant to get both players back - Bobby's very important to us obviously because we've been missing him both him and Jackson," senior coach Ken Hinkley told portadelaidefc.com.au.
"When you lose your two key backs, it makes a large difference when you get one part of it back.
"Gus has been restricted by injury a little bit this season, but as it happens we think he's coming back to us this weekend in really good shape."
Preview: Round 19
They form two of three changes to the side, with the Power to confirm one more change when it releases its final team of 22 on Friday afternoon.
Matt White will miss the game with a sore groin, while Aaron Young will miss up to three weeks recovering from a minor foot injury.
The retired Dom Cassisi is the third omission from the side.
It will be left to one in-form SANFL player to return to the side, with Kane Mitchell, Andrew Moore, Jake Neade and Karl Amon all in the mix after being named on the extended bench.
Amon would play his first AFL game if selected and, although lower in the pecking order behind AFL-experienced and consistent SANFL performers Mitchell, Moore and Neade, is a prime example of the depth of the club's list.
He was the club's best-on-ground against North Adelaide in the SANFL three weeks ago.
White suffers groin issue
"Certainly Kane has played most of his recent footy in the AFL in the past few months, and went back to the SANFL last week and curbed Crouch's influence on the game as well as won the ball himself.
"Moore has been a bit unfortunate with injury this year and would have been used a lot more if not for them.
"He's played two games in the SANFL and was in really good form, so we'll give him a look as well.
"Karl's probably still a bit back from the other three - because Jake's been in outstanding form in the SANFL as well - but Karl's an outstanding example of how our Magpies SANFL program has been able to get our boys AFL-ready much quicker."
"Unfortunately with a Sunday game, Thursday's not always the best time to name a final team so we'll see how everyone goes.
"We just need to make sure we pick the right guys in the squad to give us the most flexible choice for the game."
Seven named in extended SANFL team
Port Adelaide has also named seven players in its extended SANFL lineup.
Tom Logan headlines the inclusions after missing last week's comprehensive victory over Adelaide in the SANFL Showdown.
He's joined on the named field by Sam Gordon, who if confirmed on Friday will make his League debut, and Louis Sharrad.
SANFL Preview: Round 15
Robbie Young, Danny Butcher, Zac Hawkins and Ben Sawford join Jake Johansen on Port Adelaide's extended bench.
Tom Clurey will miss this weekend's game with a minor hamstring complaint.
The final team of 21 for Saturday's SANFL match against South Adelaide at Noarlunga with be confirmed on Friday afternoon.
Port Adelaide Round 19 squad v Collingwood
FB: Jarman Impey, Alipate Carlile, Tom Jonas
HB: Matthew Broadbent, Jack Hombsch, Jasper Pittard
C: Jared Polec, Ollie Wines, Hamish Hartlett
HF: Robbie Gray, Justin Westhoff, Angus Monfries
FF: Paul Stewart, Jay Schulz, Chad Wingard
Foll: Matthew Lobbe, Travis Boak, Brad Ebert
Interchange from: Cam O’Shea, Kane Cornes, Andrew Moore, Jake Neade, Kane Mitchell, Ben Newton, Karl Amon
Into 25: Amon, Carlile, Mitchell, Moore, Monfries, Neade
Out: White (groin), Young (foot), Cassisi (retired)
New Player
Karl Amon – 2013 AFL Draft Pick No. 68
Port Adelaide Round 15 squad v South Adelaide
FB: Nathan Krakouer, Ben Haren, Daniel Flynn
HB: Henry Slattery, Lewis Stevenson, Anthony Biemans
C: Sam Gordon, Steven Summerton, Louis Sharrad
HF: Darcy Byrne-Jones, John Butcher, Sam Russell
FF: Brendon Ah Chee, Mitch Harvey, Mason Shaw
Foll: Angus Bruggemann, Tom Logan, Sam Gray
Interchange from: Robbie Young, Jake Johansen, Ben Sawford, Zac Hawkins, Danny Butcher
Into 23: Logan, Gordon, R. Young, D. Butcher, Sharrad, Hawkins, Sawford
Out: Moore (AFL), Neade (AFL), Amon (AFL), Mitchell (AFL), Clurey (hamstring)
Port Adelaide Round 15 Academy team v South Adelaide
FB: Tom Corcoran, Harris Jessen, Tom Phelps
HB: Tom Gray, Jackson Williams, Matt Venter
C: Justin Mills, Jack Cooper, Brad Coulson
HF: Sean Davidson, Sidney Masters, Anthony Prior
FF: Declan Hamilton, Ciaran Hollingworth-Hughes, Jack Haarsma
Foll: Jonathan Ross, Matthew Williams, Will Northeast
Interchange from: Kyron Dixon
Into 23: Logan, Gordon, R. Young, D. Butcher, Sharrad, Hawkins, Sawford
Out: Moore (AFL), Neade (AFL), Amon (AFL), Mitchell (AFL), Clurey (hamstring)
