Chinese teen tennis qualifier Shang Juncheng overcame two rain delays and advanced to the ATP Atlanta Open semi-finals on Friday by defeating Australia's Max Purcell 7-6 (7/3), 6-4.The 19-year-old left-hander from Beijing shrugged off rain stoppages late in each set to reach a Saturday semi-final match against Australian fourth seed Jordan Thompson, who ousted fifth-seeded Spanish wild card Alejandro Davidovich Fokina 7-6 (7/5), 4-6, 6-3.