Port Adelaide is on the verge of qualifying for consecutive AFL finals series - and the real work is still ahead of a team determined to make the season count.

"If you do get five or six weeks right, things can really turn for you," Port Adelaide defence coach Brett Montgomery said as the fall-out of a wild round 17 proved how open the premiership race remains.

Montgomery was part of the 2016 Western Bulldogs unit that proved - by winning four consecutive finals after finishing outside the top four - that the AFL premiership is claimed by the best team in September.

"Momentum and confidence," says Montgomery of the key to success in September. "We have shown at times that we can generate that. But even when we have beaten teams that are below us, we have not played four quarters.

"And clearly against the good teams we don't look like we can generate that momentum.

"There is still a fair stretch of the season to go."

Fifth-ranked Port Adelaide will seek its 12th win of the home-and-away season on Saturday evening, a marker generally regarded as the cut-off point to the top-eight AFL finals.

The opponent - ninth-placed St Kilda, with eight wins from 16 matches - put itself in the frame for finals calculations by upsetting top-four contender Brisbane in Queensland at the weekend.

Port Adelaide will be playing at the Melbourne Docklands for the second time in three weeks. 

At selection, Port Adelaide will be forced to cover the loss of midfielder Zak Butters (right knee). But defender Ryan Burton (groin) is fit to play - and from the SANFL there is midfielder Xavier Duursma, experienced defender Hamish Hartlett, ruckman-forward Peter Ladhams and midfielder-defender Riley Bonner to consider in match committee.

"Ryan will be fine," Montgomery said on Monday at Alberton. "He had some groin tightness but everyone is positive where he will be this week."

Duursma made his SANFL debut on Saturday, his first game since recuperating from the knee injury suffered against Richmond on April 9.

"It is great to see Xavier out there," Montgomery said. "That is the No.1 thing. Whether he is up for selection is not for me to say right now, but he has certainly made a lot of people happy seeing him out there running around.

"He certainly ran out the second half (against Norwood) a lot better than how he started.

"For quality, polish and adventure in our ball movement, Hamish Hartlett has to be part of that (selection) conversation. No certainty, but he played well enough at the weekend to be part of that conversation."

The post-mortems of the 31-point loss to Melbourne at Adelaide Oval on Thursday night has a well-repeated focus on another loss to a top-four side. But Montgomery notes some new themes within the long-running storyline.

"Part of that game (against top-ranked Melbourne) was a little bit different to some of the things that have popped up in our other defeats," Montgomery said. "The consistent one is, they (Melbourne and fellow top-four contenders Brisbane, Geelong and the Western Bulldogs) are all better teams than us right now.

"We're the fifth-best team with work to do.

"There were some clear parts of the game where we allowed the intercept game of the Demons to take a hold of us. And part of that was their outstanding work, but a big pat was some lack of polish and class and composure on our part as well.

"That has not always been the feature of our other losses. It was certainly a big part of this one.

"If we had taken some more opportunities and shown some more composure (against Melbourne) and class and not put excess pressure on ourselves ... we would have been right in that game. Unfortunately, that is not the way it played out.

"We walk away knowing we still have the game - with some returning soldiers and some tightening of a few things - that we won't be far away."

Port Adelaide worked to a cluttered attack on Thursday night, losing the powerful transition from defence to attack noted earlier in the year.

"That is not just us," Montgomery said. "A lot other clubs, particularly around the past two-three weeks, teams are generally pretty tired. There is always teams around this time of the year that have made a clear decision to take away the opposition's game and not focus as much on their own games. 

"That has not necessarily been the case with us, but we are certainly having some issues with it. Part of it with us is our A-grade line-up; we have a good team, we are stretched for depth a little bit at the moment and we have had some guys come in to do jobs quite well also.

"Across the competition, it is getting harder.

"The most uncharacteristic thing that popped up (against Melbourne) is we were not as damaging when given the opportunity. “While they defended the ground really well, and they need to take a lot of credit for that, we had opportunities - and we have spent a good couple of hours looking at those missed opportunities in our own game. Take some of those and it is a very different looking game."

Port Adelaide opted to work Sydney recruit Aliir Aliir in ruck with a determined mindset to ease the batterings of forwards Charlie Dixon and Todd Marshall who have supported lead ruckman Scott Lycett in the past.

"He terrorised us when he rucked for Sydney and we saw an opportunity," Montgomery said. "Would we go there again? Probably not as a starting position. As a coach you do need to look at flexibility so that you are not locked into one thing.

"We will look for other ways ... 

"Our key forwards were getting a little banged up and they needed a one-week reprieve. It was a one-week opportunity to make sure Charlie and Todd stayed ahead of the ball.

"Scott Lycett is an outstanding ruckman. He is an even better ruckman when he gets a six or seven or eight-minute break."