Perth | Poland beat China and Australia upset Serbia to advance to United Cup semis in Sydney
Poland and Australia reached the semi-finals of the United Cup with clean sweeps over China and Serbia, the latter which saw ATP World No 1 Novak Djokovic toppled by Alex de Minaur, while there was another stellar performance from the WTA World No 1 Iga Swiatek, who beat the talented young Chinese Qinwen Zheng in…