Roundup: Poland reaches United Cup semis, Djokovic's Serbia crashes out

PERTH, Australia, Jan. 3 (Xinhua) -- World No.1 Iga Swiatek on Wednesday led top seed Poland into the semifinals of the mixed teams United Cup, while Serbia crashed out with an ailed Novak Djokovic suffering his first defeat in Australia since 2018.

Swiatek swept past Zheng Qinwen 6-2, 6-3 at Perth's RAC Arena to seal Poland's quarterfinal victory against China. After Hubert Hurkacz beat Zhang Zhizhen in the men