A match between Shuai Zhang and Angelique Kerber at the China Open was marred by an ugly fight on Sunday, involving members of the player’s box of Zhang.

According to multiple reports, Zhang’s camp was frustrated by a fan who was aggressively cheering Kerber behind them. The celebration by Kerber fans spilled into Zhang’s box after the German’s three-set victory.

One report indicates the Kerber fan yelled slurs at Zhang’s mother and spat at her, while another witness says he slapped her. The Zhang supporter was identified as her father’s friend. In the video, he appears to be going after the fan in the Steph Curry T-shirt.

“The unfortunate incident which occurred after a match (Sunday) night has been investigated and resolved,” the WTA said in a statement. “The individual involved, a guest of Zhang Shuai’s father, will not be returning to the China Open this week.”