Neymar limped off after just 12 minutes of Brazil's 1-1 friendly draw with Nigeria in Singapore on Sunday with an apparent thigh injury.
The 27-year-old was replaced by Philippe Coutinho but gave a thumbs-up to the crowd as he headed down the tunnel.
A team spokesman said Neymar "felt discomfort" in his left thigh and would be examined by PSG doctors once he was back in France.
Neymar was making his 101st appearance for Brazil, having reached his centenary against Senegal on Thursday.
The PSG forward would have been hoping to beat Ronaldo's record of 62 goals for Brazil, which he is just one strike behind.
Neymar has been plagued by injury this year and missed the Copa America this summer because of an ankle injury.
A serious foot injury also ruled him out for several months before the World Cup, although he was able to play in the tournament for Brazil.
Casemiro strikes - but Brazil's mini-slump continues
Nigeria took the lead in Singapore in the 35th minute 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.
The draw extends Brazil's winless run to four games.
Since lifting the Copa America in July, Brazil have also drawn with Colombia and Senegal and lost to Peru.
"The result was not good enough," said Brazil boss Tite.
"The Brazilian national team must win, looks to win, wants to win, needs to win. It means nothing if you have ball possession but you do not create opportunities. We had, but we were not effective."