Super Eagles home-based goalkeeper Ikechukwu Ezenwa along with assistant coaches, Alloy Agu, Imama Amapakabo and team administrator Dayo Enebi have been unable to get their visas to Singapore.
The Nigeria Football Federation (NFF) are however still hopeful that the delegation will get their visas before Thursday, October 10.
The Super Eagles camp at the Fairmont Hotel has already opened with a couple of players expected on Wednesday.
A host of Super Eagles players are already in camp. The likes of Wilfred Ndidi, Alex Iwobi, William Troost-Ekong, Samuel Chukweuze and Chidozie Awaziem arrived in Singapore in the early hours of Wednesday.
Brazil have been in town since Monday as they prepare for two friendly games. First against Senegal on Thursday, October 10 and against Nigeria on Sunday.