Port were on Monday issued a "please explain" by the AFL after club doctors failed to put Aliir Aliir through a concussion test following the defender's collision with teammate Lachie Jones on Saturday night.
While Jones was subbed out of the Showdown loss against Adelaide because of a migraine, Aliir returned to the field.
Port said the two players passed SCAT5 protocols, but have since shown symptoms consistent with concussion.
Jones and Aliir will both sit out this Saturday night's crunch game against Geelong at GMHBA Stadium.
Cassie Burton, the partner of former Port utility Sam Mayes, said the current spotlight on Port's concussion situation "doesn't surprise me" and it made her "sick".
"Sam's played concussed after they strapped his head and sent him back on the field," Burton wrote on Twitter, accompanied with a picture of Mayes' head bandaged during his AFL career.
"He's also pulled himself out of the AFL side as he wasn't feeling right from a separate head knock. It's scary to witness."
It is understood Mayes was sent back out on the ground in a SANFL semi-final playing for Port in 2019 after a head knock. He later took himself to the bench because he was feeling unwell.
Mayes later had no recollection of Port's thrilling four-point victory after the match, which put the club into a grand final.
In 2021, the former Brisbane Lions player was named in Port's AFL team despite having a head knock playing in the reserves a week earlier.
Leading up to the match, Mayes reluctantly withdrew himself from the team after experiencing concussion symptoms, despite attempting to nail down his spot in the senior side.
Mayes' AFL career ended at the end of last year following 121 games for the Lions and Port across 10 seasons.
AAP has reached out to Port for comment on Mayes' situation.
The AFL on Monday said its chief medical officer Dr Michael Makdissi was liaising with Port in monitoring the condition of Aliir and Jones.
Concussion is now a massive issue in the game with the AFL cracking down on dangerous tackles this season.
A number of former players are suing the league and their clubs, seeking compensation for the effects of concussion from their careers.
In 2016, the AFL fined Port Adelaide for how they handled a head knock to player Hamish Hartlett.
Port were fined $20,000, with $10,000 of that suspended to the end of 2018, because they failed to follow AFL protocols.
Last season, Power players Tom Jonas and Zac Butters also had a clash of heads in a game against Richmond and were forced from the field.
Jonas and Butters returned to the ground and the AFL later said it was satisfied how the club handled the situation.
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