Paris St-Germain forward Neymar limped off after 12 minutes as Brazil were held to a 1-1 friendly draw by Nigeria.
The 27-year-old walked off holding his left thigh and could be a doubt for the Champions League game against Club Bruges on 22 October.
Rangers’ Joe Aribo gave Nigeria the lead in the first half as he slotted past Manchester City’s Ederson.
Real Madrid’s Casemiro prodded in from close range to equalise just after half-time.
After the match Brazil manager Tite said Neymar “felt a muscle injury” and was substituted as a “precaution”.
Despite having 70% possession in Singapore, Brazil were unable to find a winner to remain winless in this international break after drawing 1-1 with Senegal on Thursday.
Neymar, who was playing his 101st international, is now a doubt for PSG’s Champions League meeting with Club Brugge on October 22. He has missed the first two rounds because of a UEFA suspension.
He was injured while on national duty back in June when he hurt an ankle in a friendly against Qatar. It ruled him out of the Copa America which Brazil went on to win.
If the injury was bad for Neymar then the result was disappointing for Brazil it is their fourth successive match without a win.