PORT Adelaide coach Matthew Primus has given a damning assessment of the club's latest capitulation, accusing his team of raising the "white flag" in the 45-point loss to North Melbourne at AAMI Stadium on Sunday.

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The Power started well and led by eight points at the 12-minute mark of the second quarter, but their intensity dropped away sharply midway through the term.

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Led by dominant ruckman Todd Goldstein and influential midfielders Jack Ziebell, Daniel Wells and Levi Greenwood, the Kangaroos won the clearances 17-6 for the quarter.

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The Roos gave in-form forward Drew Petrie ample opportunity, sending the ball inside 50m on 20 occasions and for the 11th time in 13 games this season, Port Adelaide was outscored in the second quarter.

The trend continued in the third term, with North Melbourne piling on six goals to the Power's one.

The home team rallied to win the final quarter, but the result was never in doubt.

It was Port Adelaide's seventh 40-plus point defeat this season, and Primus said the club had developed an unwanted reputation for "rolling over" in recent seasons.

"In the last quarter when it didn't matter we decided to stand up and be competitive," Primus said.

"We just don't have the ability yet to remain consistently competitive…in the second and third quarter we rolled over to a fair extent and cost ourselves another game.

"That's been an issue for us for a few years now and it's still rearing its head. When the opposition come at us we fight back, but when they come at us again we just concede too much and that's irrespective of whether we've got 10 first-gamers in or 10 200-gamers in.

"That's the history that's been with us over the last couple of years.

"We need to keep getting better at it and our youth need to keep realising that when the momentum starts to shift we actually need to put our hand up instead of the white flag."

Goldstein amassed a club-record 54 hit-outs against four-game player Matthew Lobbe, who was dropped to the SANFL reserves during the week but called up to the team when No.1 ruckman Dean Brogan injured his hamstring at training.

Like his team, Lobbe started the game well, but couldn't sustain the effort.

The Power were beaten 27-8 in the centre square hit-outs, but Primus said his midfielders and not Lobbe were to blame for the clearance differential after quarter-time (41-22).

"It was more our midfield's inability to be aggressive and competitive enough to stop the ball getting kicked the other way," he said.

"[The Kangaroos] had as many kids as us out there tonight, especially through the middle…and I thought they were pretty special in the contested stuff in the second and third quarters.

"Tonight it was a fair bit in the centre square…our midfield allowed our backs to be under too much pressure and it certainly cost us."

Primus has used 34 players this season and repeatedly dropped experienced players, including Kane Cornes, Danyle Pearce, Brett Ebert, Jacob Surjan and Steven Salopek back to the SANFL in a bid to find a mix of players capable of delivering a four-quarter performance.

He vowed to continue making sweeping changes in the latter part of the season, but is likely to be hamstrung at selection in the immediate future because of injuries sustained in the loss to North Melbourne.

Promising, but injury-cursed midfielder Hamish Hartlett dislocated his troublesome shoulder in the final quarter.

Hartlett's shoulder slipped back into place easily, but he didn't return to the field and is in doubt for the clash with the Brisbane Lions next week.

Defender Jasper Pittard was substituted from the game in the first quarter after injuring his hamstring and is expected to miss three games.

Full-back Alipate Carlile aggravated an existing hip complaint and finished the game on the bench, while Brogan remains under a cloud.