The Chicago Cubs have banned a fan indefinitely from Wrigley Field for making an alleged racist gesture.
The incident took place while former Cubs player Doug Glanville, who is black, was working as an on-field reporter during Chicago's 5-2 win over the Miami Marlins on Tuesday.
Cameras picked up the fan making a gesture behind Glanville's back.
The Cubs concluded the gesture was "more likely than not" racist in nature and issued a ban.
Fans watching the Tuesday night broadcast first noticed the thumb-and-forefinger 'OK' hand gesture that has become associated with white supremacy.
Cubs president Theo Epstein said the incident was "truly disgusting" and told reporters on Wednesday the person would "never be welcome back to Wrigley Field".
Though the fan's face was not shown on camera, the Cubs were able to track down the fan in question.
"After a review of last night's broadcast footage, we concluded this individual's actions violated the guest code of conduct," read a Cubs statement.
"As a result, after repeated attempts to reach this individual by phone, we sent a letter to the individual notifying him of our findings and our decision that, effective immediately, he will not be permitted on the grounds of Wrigley Field or other ticketed areas indefinitely."
Mr Glanville applauded the team's responsiveness.
"They have displayed sensitivity as to how the implications of this would affect me as a person of colour," he said.
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It is unclear how the inverted 'OK' gesture became associated with "white power".
The symbol apparently began as an online hoax before it was adopted by far-right sympathisers and even some Trump supporters to goad liberals.
In September, a US Coast Guard employee was removed from duty after he was seen apparently making the sign while his colleague was on air with MSNBC News.