With his white-rimmed glasses and his easy-going attitude, Chung Hyeon has become one of the most talked about players at the Australian Open. The 21-year-old has already made history as the first South Korean to reach a tennis Grand Slam quarter-final. Today he beat American player Tennys Sandgren and will now come face-to-face with Swiss star Roger Federer at the semi-finals . Chung, who comes from the South Korean city of Suwon, began his tennis career at the age of six. His doctor had recommended that looking at the colour green would help with his weak eyesight. At the age of 13, he moved to the IMG tennis training academy in Florida where he would be for the next two years. He later returned to South Korea and in 2014, turned pro.