Brandy performed in front of 40 people at a 90,000-capacity stadium over the weekend.
The singer was part of the Nelson Mandela Sport and Culture Day at the FNB Stadium in South Africa, but the crowd was unaware she was scheduled to take to the stage.
After a full day of performances from various acts, the audience presumed the day had finished and left the venue, leaving just 40 people to watch Brandy perform two songs.
"I have no words for what I just witnessed," fellow artist Kabomo tweeted after the incident.
After being asked why the audience left, he replied: "It was late. People didn't know there was a concert after the games. No one knew Brandy was around. Maybe a 40 people audience."
