Alexander Zverev under injury cloud after withdrawal from United Cup quarter-final tie

Alexander Zverev withdrew from his quarter-final singles match at the United Cup with a bicep injury.

Spearheading defending champion Team Germany's campaign, Zverev was scheduled to play Kazakhstan's Alexander Shevchenko in the men's singles leg in Perth on Wednesday afternoon.

However, after appearing concerned with his right arm, Zverev was replaced by Daniel Masur in the line-up at the eleventh hour.

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With the Australian Open less than two weeks away, Zverev will be hoping the complaint is the result of muscle soreness and nothing more serious.

The tournament's official social media platforms confirmed that Zverev had sustained a bicep strain.

"Alexander Zverev has withdrawn from the United Cup due to a bicep strain," organisers wrote on X on Wednesday.

"Daniel Masur will take his place for Team Germany in today's singles match against Kazakhstan."

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If Zverev is sidelined further by the injury, he will be heavily restricted leading into the first major of the year.

The world No.2 defeated Brazilian Thiago Monteiro in straight sets on Sunday before backing up with a 6-2, 6-0, 6-2 win over Zhang Zhizhen of China on Monday — his first two singles matches of the new season.

In positive signs for the 27-year-old, Zverev moved to Team Germany's courtside bench during the first set of the men's match.

Zverev is chasing an elusive grand slam singles title after runner-up performances at the US Open in 2020 and Roland-Garros last year.

Kazakhstan won through to the semi-finals 2-0 after Elena Rybakina's straight-sets victory was followed by Shevchenko's triumph over Masur.