According to www.lasgigantes.com.ar, the CD Alcazar small-forward suffered severe pains in one of her knees and has decided not to take part in the Olympic qualifying tournament which will take place in Valdivia, Chile, from September 26 to 30.
The news comes as a massive blow for Eduardo Pinto's side, with Mendoza one of the most accurate players from three-pointers.
Argentina begin a series of friendlies against Cuba in Rosario on Wednesday as part of their warm-up to the FIBA competition.
On Thursday, they meet again in Gualeguaychu, with a possible third game scheduled to take place in Buenos Aires on Friday.
The FIBA Americas Championship offers a place at next year's Olympic Games for the winners, while teams finishing from second to fourth will advance to a repechage tournament.
Argentina have been drawn in Group A, alongside Brazil, Mexico and hosts Chile, while Group B will see the United States, Cuba, Canada and Jamaica do battle.
Winter Youth Olympics 2020