The Selecao number 10 was called up by his country despite missing Paris Saint-Germain's past three matches with a groin strain.
Neymar was always expected to miss the Brazil v Venezuela fixture on Saturday (AEDT), but he has now also been ruled out of the visit Uruguay on Wednesday (AEDT).
Brazil will again be without its talisman for that match, as team doctor Rodrigo Lasmar explained.
"We were hopeful that he could play," he said. "That's why we brought him to Brazil.
"He has improved but not enough so that he'll be ready for the game on Tuesday [Wednesday AEDT] against Uruguay. We have decided to release Neymar."
Brazil has won both of its two fixtures so far in the qualifying campaign, with Neymar hitting a hat-trick last time out against Peru.