A brawl broke out in Beijing after Angelique Kerber's opening-round win over Zhang Shuai.
Video of the melee was posted on social media. It's not entirely clear who started the fight.
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Reports say vocal Kerber fans, seated directly behind Zhang's support box, were celebrating the 10th-seeded German's victory when matters took an ugly turn.
Some reports claim a Kerber fans spit toward Zhang's mother, seated in her support box, while others claim unruly fans of both players escalated taunts and shots into shoves and punches.
Video shows a man in a blue shirt throwing multiple punches and kicks at another fan.
The WTA released a statement saying one man involved was a guest of Zhang Shuai's father and he has been banned from the China Open for the rest of the week.
“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.”