Mile Jedinak has signed a letter alongside France captain Hugo Lloris and Denmark captain Simon Kjaer urging the FIFA President to overturn Paolo Guerrero's drug ban.
Guerrero - of Bayern Munich, Hamburg and Corinthians fame - is Peru's all-time leading goalscorer with a record of 32 strikes in 86 appearances.
But the 34-year-old was banned from taking part in June's World Cup campaign after testing positive for a banned metabolite (performance enhancing substance found in cocaine) after Peru's World Cup qualifier against Argentina last October.
The forward was originally banned from all FIFA competitions for a year, which would have kept him out of Russia had the ban not been reduced by FIFA, after an appeal, to six months.
But the Court of Arbitration in Sport (CAS) then overruled FIFA's sanction and imposed a 14-month ban.
CAS released a stament after the ruling, recognising that FIFA's six month ban didn't fit within its guidelines.
"The CAS Panel confirmed the existence of an ADRV [anti-doping rule violation] committed by Mr Guerrero, but also accepted that he did not attempt to enhance his performance by ingesting the prohibited substance," the CAS statement read.
"However, the panel considered that the player did bear some fault or negligence, even if it was not significant, and that he could have taken some measures to prevent him from committing the ADRV.
"Considering that, in case of no significant fault or negligence, the sanction should, in accordance with the applicable FIFA rules, be in the range of one to two years of suspension, the CAS Panel considered that the appropriate sanction would be 14 months in light of the Mr Guerrero's degree of fault."
But in response to public backlash against the decision, the captains of each of Peru's World Cup Group C opponents, including Jedinak, have released a letter campaigning for the decision to be overturned.
"Peru is returning to football's ultimate stage after a 36-year absence and we believe Paolo Guerrero should be allowed to lead his nation and celebrate what will be a career highlight," the statement said.
"Given the exceptional circumstances which pertain to this matter, we respectfully ask the FIFA Council to show compassion with Paolo Guerrero who has given his utmost for his national team since 2004 and has recently achieved one of the highest possible honours for any national team player – qualifying for the FIFA World Cup.
"In our view, it would be plainly wrong to exclude him from what should be a pinnacle of his career - an achievement he has worked so hard for, and for so many years - on the basis of a finding which confirms that he did not intend to cheat and did not intend to enhance his performance with prohibited substances.
"As such, we turn to the FIFA Council and kindly put forward an urgent request for clemency by asking the FIFA Council to temporarily interrupt the ban imposed on Paolo Guerrero during the 2018 FIFA World Cup in Russia, with the suspension to recommence at the conclusion of Peru's participation in the competition.
"We believe that in the interest of fairness and proportionality, and taking into consideration the exceptional circumstances of the present matter, Paolo who – as everyone agrees did not cheat – should be able to participate with, and against, his fellow professionals in the FIFA World Cup. As such, we strongly believe that a temporary interruption would be the equitable and rightful solution."