Online Game Day
Gray kicked two goals in the Power's loss to Geelong last weekend, but failed to complete training on Wednesday night and was a no-show at training on Friday.
Coach Matthew Primus said the injury-ravaged goalkicker would need to pass a fitness test on Saturday morning to play against the Crows.
"We're not sure about Robbie. He's got a leg complaint which flared up Wednesday night at training," Primus said on Friday.
"Rather than training today we thought the best chance [of Gray playing] is if he can train tomorrow and get through that. We'll have to see how it unfolds tomorrow morning."
Midfielder Steven Salopek also missed training on Friday to attend the birth of his second child, but is certain to play on Saturday night.
The Power have already made five changes to the team that lost to the Cats last weekend, with Kane Cornes, Danyle Pearce, Jason Davenport, Daniel Stewart and Jarrad Irons all omitted.
Cornes' omission has put an end to a run of 174-consecutive games.
The premiership player and dual All-Australian won't play for SANFL club Glenelg, despite not being named as an emergency for Port Adelaide.
Primus suggested Cornes would benefit more from a solid week on the training track and a clarification of his new role on the wing/across half-back than he would by playing in the SANFL.
"We're just trying to freshen Kane up mentally and physically this week. We know what he can do playing and fitness-wise, so it was a matter of giving him the weekend off," he said.
"We want to ease his load and talk him through the roles he's playing with us now. Like a few of our players, Kane's got to get back into some really good form, look at the role he's playing and be able to do it to the best of his ability and with some clarity.
"He's played a certain [tagging] role for so long and now he's got something different to go with."
Primus has showed he isn't afraid to make tough decisions on experienced players at selection since taking over from former mentor Mark Williams halfway through last season.
Daniel Motlop, Chad Cornes and now Pearce and Kane Cornes have all been dropped during Primus' short tenure, but the first-year coach denied he was trying to make a statement.
"If [dropping Cornes and Pearce] sends a strong message it does, but it's more about finding a 22 that play the way we want to play and they way I want them to play," he said.
"After three losses like we've had I think most players would [already] be jumpy about where they're at. They believe in themselves, but they know that if they keep going like that eventually there are going to be changes made."
The Power, who have won four of the last five Showdowns, have a history of lifting for games against their cross-town rivals.
Primus was hopeful the Showdown would have the same effect this week, but said his team needed to start producing similar spirited efforts against its other opponents.
"We're not going to produce anything as a football club … if we rely on a game or an opposition to get ourselves up," he said.
"We're looking to get on the winning side of the weekend's game, but [if we do] we want to produce that same stuff the next and the week after."
The Crows also have injury concerns ahead of Showdown 30, with defender Richard Tambling (ankle) ruled out of the clash and star forward Taylor Walker in doubt with a buttock injury.
Katrina Gill covers Port Adelaide news for afl.com.au. Follow her on Twitter: @AFL_KatrinaGill
