Silas Gnaka converted a penalty as the Ivory Coast surprised Nigeria 1-0 in Cairo Saturday in the Group B opener at a qualifying tournament for the 2020 Tokyo Olympic Games.
Gnaka scored after Olisa Ndah committed a foul that resulted in him being red-carded, leaving Nigeria to play the final 20 minutes a man short.
Nigeria lacked captain Azubuike Okechukwu and Taiwo Awoniyi after their Turkish and German clubs refused to release them ahead of the November 11-19 international window.
Many European clubs did agreed to free players for the tournament, which doubles as the Africa U23 Cup of Nations, even though it started and will finish outside the window.
Nigeria have won gold and silver medals, Cameroon gold and Ghana bronze at previous Games.