PORT ADELAIDE is challenged. Extremely challenged by injury, a four-game losing streak that has dropped Ken Hinkley's team to fourth on the AFL ladder ... and the real threat of a finals-chasing Greater Western Sydney at Adelaide Oval on Sunday.

The strength in adversity within the playing group remains unchallenged in Hinkley's eyes. He certainly is not seeing any fall in energy or ambition from his troops as the final stretch to the top-eight series tests Port Adelaide's want to hold rights to a home qualifying final in September.

"This team has dealt with some challenges across the past couple of years," Hinkley said on Saturday. "Our form suggests we are certainly challenged. 

"But I am really optimistic of what this group is capable of. And they believe.

"It is important there be balance (in assessing Port Adelaide's jump in form from 13 consecutive wins followed by four consecutive losses). Our reviews across the past three weeks have been with great balance - and with enough positivity around what we are doing well while we have not been able to get the result we want.

"You have to help your team believe ... that is our job right now. We believe in them."

For the fifth consecutive week the forced turnover of players at selection has continued. This time, Port Adelaide has restocked its defensive options with the return of Aliir Aliir and Lachie Jones from concussion protocols and Miles Bergman from illness while losing Trent McKenzie with a knee injury.

There was another change after selection on Thursday night with the loss of novice ruckman Dante Visentini (quad) at training - and Hinkley was still not using ink on his team sheet during the captain's run at Adelaide Oval on Saturday morning.

"We're dealing with illness around the footy club, but we feel we have come out the other end," Hinkley said while checking on the health of his assistant coaches. "Hopefully, we will be as selected ... but it does not mean we will.

"I am optimistic. But I was pretty optimistic last week until Saturday morning (in Geelong) when we made three changes."

RUCK ROSTER: Jeremy Finlayson returns from illness to lead the Port Adelaide ruck - and play a significant role in loading the scoreboard while key forward Charlie Dixon is on the sidelines until finals with a foot fracture.

Planning the ruck-forward mix with Finlayson and the inexperienced Ollie Lord will be another moving script this weekend.

"That is the art of the game and as the game unfolds you need to know which lever to pull," Hinkley said. "You have to be flexible enough to know it may not go according to script. We, as coaches, prepare for every alternative - all the what ifs. Our flexibility is equally important as the players.

"Wait and see ... what's the weather like, what are the opposition threats, what are our opportunities. We have a plan. But I am not going to put that on the table now."

Visentini was injured at training on Thursday night forcing Port Adelaide to add Sam Hayes to the emergency list while he is recovering from a shoulder injury.

"Dante got a little nick in his quad; we won't take any risk," Hinkley said. "It is his left leg, not his kicking leg. Ultimately, it should be pretty short term. He is a young player we are really excited about.

"Sam Hayes is fine to play if we need him. He trained Thursday night and is fine. He is right to play if he had to be picked."

ALIIR AND JONES: "They have been through the 12 days of (AFL concussion) protocols and each step takes its turn; their last step was Thursday and they have been cleared to play," Hinkley said. "They have passed all the medical requirements that they need. Safety is first and foremost our ultimate aim. We are really comfortable both players are ready to play with a clear mind."

INJURY CRISIS: "That is our challenge at the moment," Hinkley said. "There is no doubt it plays a part in some of our results. There are a significant couple of games (Collingwood and Geelong) where we played really well but we did not win. That may - or may not - be due to personnel, in and out of the team. But every side is dealing with that. I don't have too many problems with that.

"We still have to maximise the opportunity we have put ourselves in from the first three quarters of the season. We are having out little tough trot with the availability of players. It is part of the season. So, wait until you get to the end of the year - reset, see where you are at and make the most of your opportunity. 

"The next three weeks (GWS, Fremantle and Richmond) is critical to our finishing position. But then it becomes a whole new game. We know that."

WHISTLE WATCH: Hinkley clarified he this week sought advice from AFL umpiring director Dan Richardson on how to direct his players to defend in marking contests without conceding free kicks more so than the free-kick count from the match at Kardinia Park.

"It was about marking contests," Hinkley said. "Clarity on marking contests is really hard to accurately inform your players on which is the right and wrong way to go about it because there are so many different interpretations at times. 

"We had a really good conversation on what is the best way for us to play the game. We have given away a lot of free kicks and that has nothing to do with the umpires. That is more about how we are playing. 

"Is it an award that when you are an aggressive, assertive, attacking team that goes after the opposition that you might give away to many free kicks?

"You are always looking for clarity."

FOR THE RECORD: Of the two franchises introduced to the AFL since Port Adelaide earned promotion to the national league, Greater Western Sydney has proved most challenging. The clubs have met 13 times with Port Adelaide leading the win-loss record 7-6.

"They are as good as anyone in the competition during the past two months," Hinkley said of the revival of Greater Western Sydney under new coach and Port Adelaide premiership player Adam Kingsley. "They have a strong record at Adelaide Oval. We understand the size of the challenge that is coming our way. But every week has that enormous challenge. We expect the opposition at their best and we have to bring our best.

"That first win we need (to end the losing streak) might be a bit scrappy, a bit ugly but it will be the win you need to get going."

Port Adelaide has won the past three matches against GWS, the most recent being a 55-point win at Adelaide Oval in early July last year.

Sunday’s game at Adelaide Oval gets underway at 4:10pm. Tickets are still available for the match.