Neymar went off injured 12 minutes into Brazil's 1-1 draw with Nigeria in a friendly in Singapore on Sunday.
The Paris Saint-Germain forward, making his 101st appearance for the national team, touched the back of his leg as he left the pitch and was replaced by Philippe Coutinho.
A team spokesman said Neymar "felt discomfort" in his left thigh and would be examined by PSG doctors once he was back in France.
Globoesporte.com cited the Brazilian team doctor as saying the player was not in pain.
The draw extended Brazil's winless run to four games.
The Africans took the lead after 35 minutes when Joe Aribo found space in a packed penalty box to rifle in a low shot and grab his second goal in two international appearances.
Brazil equalised three minutes into the second half when Casemiro fired home from close range after he was quickest to react when a Marquinhos header came back off the woodwork.
Casemiro later smacked a header off the bar and Coutinho should have scored a cut back with five minutes remaining but the score remained at 1-1.
Since lifting the Copa America in July, Brazil have also drawn with Colombia and Senegal and lost to Peru.