KEN HINKLEY calls it the must-win game purely for the battle of superiority in South Australia, but there also is a pressing national agenda at stake in Showdown LIV - the prize of a top-two finish in the race to the AFL final.

"It is about the Showdown right now - and the Showdown is important to everyone in this town," said Hinkley on the eve of the 54th derby at a sold-out Adelaide Oval. 

"We are pretty disappointed we lost that (home) Showdown in round three. We don't want to lose any Showdown. They are too important. 

"The reality is - these are the two games of every year that are must-win games. We didn't win the first one; we have to win the second one."

And in the background is the premiership table with second-ranked Port Adelaide holding a one-win advantage on Brisbane that commands a superior percentage. 

"We have two teams chasing their seasons in different ways," said Hinkley of the national agenda wrapped in the local Showdown battle with 13th-ranked Adelaide that is on the edge of elimination from the top-eight race. "We have to keep winning. Right now, we are in the heart of qualifying as high as we can (with Brisbane and Melbourne eager to pounce on any slip-up made by Port Adelaide). 

"This Showdown is big for both teams. 

"We have lost our past two games (against Carlton and Collingwood), so we have a challenge on our hands. We played a really good game of football last week (against Collingwood). It was a powerful game."

Selection on Thursday night brought two major changes to the side that fell by two points to Collingwood - the benching of experienced ruckman Scott Lycett, who remains troubled by knee issues; the move of former captain Travis Boak to the tactical substitute role for his 30th derby.

Lycett's absence puts Dante Visentini into his second AFL game ahead of Sam Hayes who suffered a shoulder injury at training at Alberton on Thursday morning.

A month after being rushed off the emergency list - and out of the grandstands at the MCG to replace Lycett against Essendon - Visentini will face the major challenge of contending with the experience and Showdown spirit of Reilly O'Brien who took critical marks in defence during the round three derby at Adelaide Oval on April 1.

"Dante gets a better preparation; he gets to turn up knowing he is playing," Hinkley said of his novice ruckman. "Unfortunately, Sam Hayes hurt his shoulder on Thursday. He was unavailable full stop. Our hand was forced a little bit but we are confident Dante is a strong, young ruckman who is looking forward to the opportunity.

"We are about to find out how he plays against a really good opponent. Dante's form in the SANFL since his first little taste against Essendon has been incredible. He has shown that he has learned a lot. He is a fiercely competitive young person who will work really hard. He will best tested on that hard work because he is up against the best of the running ruckmen. I am looking forward to seeing what he can do at this level with a proper preparation; we did not give him the best chance to succeed last time. Hopefully, we have this time."

"We made the decision for Scott, mindful of his knee. We need him available as much as we possibly can. We know we can't push him through every session and every game, otherwise we will probably lose him."

Boak's move to the bench reaffirms the Port Adelaide midfield is now the province of young guns Connor Rozee, Jason Horne-Francis, Zak Butters and Willem Drew.

"We are comfortable Trav will be a very good sub for us this week," Hinkley said. "We are managing his season, his loads (as he approaches his 350th game during the finals series). He is not getting any younger. But he is still pretty important to us.

"It also is about form - we have had strong selection integrity (as noted with the dropping of captain Tom Jonas and defender Ryan Burton this season). This is more about managing Trav and making sure he gets the opportunity to take his form back to the highest level which we know is remarkably strong."

MIDFIELD POWER: Boak's absence from the starting 22 significantly changes the dynamics of the critical midfield battle.

Of the six men named in the starting midfields, Port Adelaide's players are all younger than their direct opponents. Only two have more games to their names than their direct rivals - Ollie Wines by 12 on Rory Laird and Xavier Duursma by 28 on Mitch Hinge.

Overall, the Port Adelaide six is putting up 512 games of experience against 668.

The numbers are - Dante Visentini (20 years and one game) v Reilly O'Brien (27 and 95); Willem Drew (24, 74) v Jordan Dawson (26, 104); Miles Bergman (21, 51) v Chayce Jones (23, 74); Xavier Duursma (23, 66) v Mitch Hinge (25, 38); Ollie Wines (28, 221) v Rory Laird (29, 219) and Connor Rozee (23, 99) v Matt Crouch (28, 138).

"We are definitely a much younger team around the ball," Hinkley noted. "That is okay. We have been younger all the way through this year. Scott and Trav missing add to that. But there is our development as a group through those younger mids - as much as anyone.

"If you look at the age profile of the two teams we are five years' younger than the opposition mids. That is a significant difference. But it is one we are happy to take on."

OPPO WATCH: Hinkley acknowledged Reilly O'Brien's shadow on the Showdown is significant. "That is accurate; we know what he brings to their team," Hinkley said. "He works to a midfield that he supports incredibly well. He gives them first look a fair bit of the time. He has a great record against us in Showdowns. We have to do our absolute best to quell that. It is obvious he (cuts off opposition forward thrusts with his marking) gets back and gets in the way."

CAPTAIN'S RUN: Hinkley is not concerned by the absence of some players from the final training session at Alberton on Friday morning. "We had a couple away, but I have spoken to all the boys and they are all okay," Hinkley said. "It is that time of the year; a little sniffle. We keep them away (from the rest of the group)."

CONVERSION: Left to lament poor execution on goalkicking opportunities last week, Hinkley said: "The game is about conversion ... we work on that every week. We had our opportunities against Collingwood. It was a game we let slip."

DEFENCE: It is a much changed back seven to the group that played in the earlier derby and conceded more than 100 points. "We are more than comfortable with our defensive group," Hinkley said. "It is quite significantly different to the defence we had in the last Showdown; we are optimistic by be great growth from some of those young players who are there plus the senior players of Aliir Aliir and Trent McKenzie holding their end up well."

GROUND VIEW: Hinkley went to the bench after the Showdown loss in round three. "We are doing what is best for the team and best for us is for to me on the ground with the players," Hinkley said. "It is to keep them calm and guide them when the moments get tough and tight. And we expect that to the case on Saturday night."

The match will begin at 7.10pm. Port Adelaide holds a 27-26 lead on the Showdown ledger.