Any switch of allegiance for the 18-year-old must still be confirmed by FIFA but coach Alain Giresse told a Dakar press conference Niang had said he was ready to commit to Senegal.
"He has told me he has decided. I have had contact with him, he is a player I have admired from far," the Senegalese news agency quoted Giresse as saying.
FIFA allows players previously capped by one country at junior level to play for another, as long as they held dual nationality.
Niang is among five new caps included in the squad for the match at Saint-Leu, near Paris on August 14, the Senegal Football Federation announced on Thursday.
Giresse has dropped Papiss Cisse and again ignored Chelsea forward Demba Ba, who was left out of June's two World Cup qualifiers.
The Zambia match is preparation for September's qualifier against Uganda which Senegal need only to draw to secure a berth in the final round of African preliminaries for next year's World Cup in Brazil.
(Reporting By Mark Gleeson in Cape Town; Editing by Alison Wildey)
