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.

Alexander closed games two and four for 3-1 and earned another break chance in game five. Thiago saved it and held to remain in contention. Delivering one good hold after another, Zverev added more service winners to his tally in games six and eight for 5-3.