Left-back Chaker Alhadhur started in goal for the Comoros Islands in their 2-1 Africa Cup of Nations loss to hosts Cameroon in a round of 16 showdown at the Stade d'Olembe, Yaounde.
The move comes after returning goalkeeper Ali Ahamada was barred from playing despite returning a negative COVID test result on Monday morning.
On Sunday, the islanders -- playing in their first Nations Cup -- confirmed that they would have to use an outfield player between the posts for the biggest match in the country's footballing history after all three of their goalkeepers had been ruled out.
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Stoppers Ahamada and Moyadh Oussenini were among 12 positive COVID cases identified over the weekend, while Salim Ben Boina, who was lauded for his heroics against Morocco, is still recovering from a shoulder injury.
On Monday, Comoros, whose head coach Amir Abdou is also isolating, were boosted by the news that Ahamada had received a negative coronavirus test result, and duly ended his quarantine in Garoua and flew him to Yaounde in the afternoon.
However, when the teams were revealed ahead of the last-16 meeting, Alhadhur, who plays in Ligue 2 with AC Ajaccio, was named as the Comoros' starting goalkeeper, following the Confederation of African Football ruling that Ahamada would not be allowed to participate due to the tournament's COVID protocol.
According to CAF's Medical Commission, players must isolate for five days after receiving a positive test before returning to action in the competition, meaning that although Ahamada tested negative on Monday, he will be unable to compete against the Indomitable Lions.
The Comoran Football Federation appears to have been unaware of this ruling, which had been clarified by CAF on the eve of Monday's meeting, and had been convinced that both Ahamada and defensive midfielder Yacine Bourhane, who also flew to join the team on Monday afternoon, would be able to participate.
The 30-year-old Alhadhur is one of the more experienced heads in the Coelacantes squad, having made his international debut in 2014. He's represented the likes of Nantes, Caen and Chateauroux during a career spent exclusively in French football.
Despite this late setback, Comoros -- ranked 132nd in the world -- had already made a contingency plan on Sunday, anticipating that they would be without a recognised goalkeeper for the meeting with Cameroon.
"We have met with the staff, talked things through, got all the healthy players together and tried to put things into perspective," goalkeeper coach Jean-Daniel Padovani said in Sunday's news conference.
"We have got some potential goalkeepers, and we are laughing about it, we prefer to approach it this way. It is funny.
"There are some who have shown during training sessions that they can play as a goalkeeper, but it's a strange situation, so we're working through all possible solutions."
Nakibou Aboubakari, Mohamed M'Changama, experienced Kassim Abdallah and Alexis Souahy are among the Comoros players unable to participate in the match, with the quartet all isolating in Garoua.
Comoros are currently enjoying a fairytale run in their maiden Nations Cup, having defeated Ghana 3-2 in their final group game to eliminate the four-time champions and reach the round of 16 at their expense.
Despite being without a recognised goalkeeper for the match, Comoros must play the fixture after CAF rules outlined that a team must take to the field as long as they have a minimum of 11 players available.