The world’s most expensive player, 27, had earlie hobbled off the pitch in tears following a rough tackle.
Neymar had a huge pack of ice around his right ankle as medical staff escorted him to the Mane Garrincha Stadium changing rooms.
Anxious coach Tite replaced him with Gremio forward Everton Soares on 21 minutes.
He was later photographed leaving the 72,000 ground on crutches.
The home side won the Brasilia friendly 2-0 thanks to goals from another Everton man Richarlison and Gabriel Jesus as the Premier League pair laid claims to starting places at the tournament.
Neymar was Brazil’s poster boy for the Copa America which starts in less that 10 days’ time and he faces a third major tournament of injury woe.