Neymar had a heated exchange with a fan after his late goal was ruled out, condemning his club Santos to a 2-1 defeat and leaving them in the Brazilian Serie A relegation zone.
The 33-year-old, who has had a frustrating time since returning to his boyhood club this year, went over to the stands at the end of the game with Internacional on Wednesday night to talk with a fan who appeared to be remonstrating with him.
Videos showed Neymar agitated and gesticulating, then raising a thumbs up as a teammate ushers him away.
Santos had been pushing for a comeback from two goals with Alvaro Martin Barreal scoring a minute into added time. Three minutes later, Neymar thought he had scored with a left-footed shot and celebrated in front of cheering home fans.
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But boos rang out across Vila Belmiro stadium as the referee ruled the ball had not crossed the line.
Santos are 17th out of 20 clubs in the league, where the bottom four are relegated to Serie B at the end of the season.
The former Barcelona and Paris Saint-Germain player has had a torrid time since returning: sidelined with injury, sent off for a handball and suffering COVID-19.