Basketball followers on mainland China expressed anger at the U.S. National Basketball Association on Wednesday after a fan event in Shanghai was cancelled, amid a row over free speech that has hurt the league's reputation in a key overseas market. Chinese organisers scrapped the event on the eve of a planned exhibition game between the Los Angeles Lakers and Brooklyn Nets, as the fallout spread from a tweet by Houston Rockets general manager Daryl Morey supporting recent protests in Hong Kong. Pro-democracy demonstrators have taken to the streets of the city over fears that Beijing is undermining Hong Kong's "one country, two systems" formula, which gives residents greater freedom than mainland Chinese.