Boak received a knock to his head at training on Wednesday.
The 22-year-old joined in a short skills session at Alberton on Friday, but coach Matthew Primus said he was still feeling the effects of the knock.
"Trav's feeling a bit better, but we're looking after his welfare and he's not 100 per cent," Primus said on Friday.
"It's going to be pretty much a contested game [against North Melbourne] we think, so we're not going to take the risk with him."
The Power will take two emergencies to Melbourne for their clash with the Kangaroos, as doubt lingers over the fitness of ruckman Dean Brogan.
Brogan (Achilles) was a late withdrawal from the team that lost to Gold Coast last weekend.
The vice-captain completed training on Friday and is expected to take his place in the side against North Melbourne.
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"Broges got through today okay, but we'll wait and see how he is tomorrow," Primus said.
"He's a lot better. He's not as sore as he was last Friday, but in saying that he's done nothing on it [his Achilles]. He had a jog yesterday and pulled up well.
"He got through today no worries…so we're pretty confident he'll be right."
Primus didn't reveal which player would replace Boak in the team, saying emergencies Jacob Surjan, Mitch Banner and Jason Davenport would all be considered.
Triple best and fairest winner Kane Cornes has been recalled to the team, following a standout performance for the Woodville-West Torrens reserves last weekend.
The Power were criticised for showing a lack of leadership in their capitulation to the Suns last weekend.
Cornes isn't a member of the club's nine-man leadership group, but Primus was hopeful the veteran could have a presence on Saturday afternoon.
"Kane has really stood up over the last couple of weeks and showed some leadership off the field with some of our young guys," he said.
"We're looking for some leadership. We didn't have enough players stand up on the weekend and hopefully Kane will add to that on Saturday."
Port Adelaide has copped heavy criticism since conceding a 40-point lead against Gold Coast to become the first club to lose to the fledgling Suns.
Critics have questioned the Power's mental toughness and commitment, while the club itself conceded the loss to the Suns had made it the "laughing stock" of the competition.
North Melbourne is also under pressure to record its first win after an indifferent start to the season.
Primus said he'd challenged his players to show resilience regardless of the result this week.
"We're looking for a competitive effort and for a 22, who want to compete and be resilient and hold up under a fair bit of pressure," he said.
"A win would be great for the club, but if we don't go about it in the right manner…it hasn't actually fixed up what we need to [improve] on.
"We've got to worry about the way we compete for four quarters and the way we're able to stand up under some heat regardless of whether things are going good or bad for us during a game."
Katrina Gill covers Port Adelaide news for afl.com.au. Follow her on Twitter: @AFL_KatrinaGill
