Carr, who was dropped from the Power line-up last week, is nursing an ongoing hip complaint and will have to prove his fitness later in the week to be considered for the clash against North Melbourne.
Talented first-year player Hamish Hartlett (hamstring) was restricted to light duties and remains only a slim chance of taking his place in the side on Saturday night.
Motlop, who showed promise in two AFL games last year, starred with 24 possessions and eight marks for SANFL side North Adelaide on the weekend.
Defender Steve Salopek said he expected either Motlop or Nick Lower to play against the Roos.
"Nick Lower got his chance against St Kilda and did a few good things, but obviously didn't hold his spot for the Showdown. To his credit, he played another great game for Norwood," Salopek said on Wednesday.
"Hamish has been playing a lot in defence and I'm not sure where he's at with his hamstring, but if he doesn't play I would've thought it would be out of those two or Carry to come back in."
North Melbourne is also expected to make personnel changes following its 52-point loss to Collingwood.
Forward Matt Campbell should return from a hamstring injury and Daniel Wells (hip) is also a chance to play.
Salopek noted the impressive performances of young duo Ben Warren and Jack Ziebell and said it was important his side found some consistency against an under-the-pump Roos’ outfit.
“We are having a bit of a rollercoaster ride. We need to bridge that gap between our good games and our bad games,” Salopek said.
“If you look at the draw, we’ve got the Kangaroos and Richmond in the next couple of weeks and it could really set us up to be 6-2, which would be quite good for us in the ladder standings.”
