Morocco will be without Mehdi Carcela for Africa's final Olympic qualifiers after Fifa ruled he was ineligible.
Fifa say the midfielder cannot play for hosts Morocco in an Olympic qualifier since he represented Belgium in the same competition four years ago.
Morocco coach Pim Verbeek told BBC Sport the Fifa ruling came late as it appears to be a case without precedent.
"Fifa only informed us today because they've never had a situation like this so were unsure what to do," he said.
"It is a little strange as that was a European qualifier and these are African."
Africa's final Olympic qualifying round, which features eight teams in total, is also being billed by the Confederation of African Football as the tournament's first Under-23 Championships.
Three teams will qualify for the London 2012 Games, with a fourth team going into a play-off against an Asian side next year.
Carcela, a former Belgium youth star, has already received Fifa clearance to swap national allegiances and play for Morocco - who he has represented in some friendly matches.
Verbeek also confirmed that Carcela, a team-mate of Samuel Eto'o at Russia's Anzhi Makhachkala, cannot be replaced in the squad.
"At this stage you can only replace injured players and so we will go into the competition with just 17 outfield players as you have to have three goalkeepers in the squad," he said.
Morocco begin their Group A campaign against Nigeria on Saturday before meeting Algeria and Senegal.