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.
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