Flight problems mean Nigeria are expected to arrive in Brazil less than 36 hours before their opening match of the men’s Olympic football tournament.
The delay has been blamed on a ‘logistical mix-up’ with operators of a charter aircraft.
Samson Siasia’s squad are due to play Japan at 0100GMT on Friday 5 August in Manaus.
But the squad are still in Atlanta with the charter airline refusing to leave until full payment has been made.
“The Nigerian government [sports ministry] is responsible for booking the tickets for the team to travel but we heard there is a logistical mix-up with payments,” a source close to the Nigeria Football Federation (NFF) told BBC Sport.
“The money paid by the ministry for the charter flight did not hit airline’s account on Tuesday so they refused to fly the team to Brazil.”
The problems seem to have happened due to the money having to go through different bank accounts and currency conversions.
“It is a cumbersome exercise but they should have started the process much earlier, which NFF was pointing out. This issue has nothing to do with the NFF,” the source explained.
He added that everyone in the NFF was “disturbed” by the situation because Nigeria’s first game is on Thursday when they take on Japan in Manaus.
The BBC has spoken to several players in the party, who say they do not yet know when they will be travelling.
One of the players explained: “We’ve been told to get ready to fly out in few hours but that’s been the story since last week.”
Nigeria, who are pitted in Group B of the Rio games alongside Sweden, Colombia and Japan, boast a proud Olympics record.
Exactly 20 years ago, they made Olympic football history in 1996 by becoming the first African and non-European and South American team to win the gold medal.
They also finished runners-up at the 2008 Beijing Olympics, where current under-23 coach Siasia also coached the ‘Dream Team’ in China.
They will begin their campaign against Japan on the opening day, then play Sweden before wrapping up their group match against Colombia.