No. 2-ranked Alexander Zverev withdrew from the United Cup mixed teams tennis tournament on Wednesday with a biceps strain less than two weeks from the start of the Australian Open.

Elena Rybakina's Kazakhstan dumped defending champions Germany out of the United Cup on Wednesday with Alexander Zverev sidelined by an arm injury barely a week away from the Australian Open, while top seeds USA beat China to reach the semi-finals.

Kazakhstan advanced to the United Cup semifinals with a victory over a German team playing without injured world No. 2 Alexander Zverev.