When Novak Djokovic won his third China Open tennis title by beating Jo-Wilfried Tsonga in straight sets in Beijing this month, he offered a surprise celebration dance - a bit of Gangnam Style invisible horse riding. Everyone got the reference. The song by South Korean rapper Psy, who performs in Hong Kong next month, became a worldwide viral video hit thanks to the accompanying choreography, and in mainland Chinese cities the song is played everywhere, loudly and constantly. China was on to Psy long before the YouTube video that made him a hit in the West. On the mainland, he's been affectionately known as Uncle Bird since his 2001 debut album, Bird . Although YouTube is banned on the mainland, clips from America's Ellen DeGeneres Show showing Psy teaching the dance to pop star Britney Spears has become almost as popular in China as the song itself. Mainlanders, from university students in Ningbo to a bride in Nanjing , have also made their contribution to the vast number of videos parodying Gangnam Style circulating on the internet. Of course, it didn't take long for someone to cut and dub the Chinese Red Army Choir - a long favourite source of inspiration for mainland internet users - to sync with Gangnam Style . Why is everyone so obsessed? Jilin Normal University student Zhang Yi listed the reasons without hesitation: "The horse-riding dance is fresh; Uncle Bird's rap is catchy; the parody videos are so funny, and many US artists like Britney Spears love it." Drawn by the catchy tunes, flashy singers and synchronised dances, mainlanders have been increasingly listening to Korean pop music since the late 1990s. In 2008 Nobody by Wonder Girls swept the mainland, followed by Sorry, Sorry by boy band Super Junior in 2009, with white-collar workers performing their own versions at their companies' spring festival parties. This year, it's Gangnam Style .