World 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. The 27-year-old Zverev won his opening two singles matches of the season against Brazil’s Thiago Monteiro and China’s Zheng Zhizhen at the United Cup. He was scheduled to face Alexander Shevchenko of Kazakhstan in Perth in the United Cup quarterfinals, but withdrew at the last minute with Kazakhstan leading the tie 1-0 after Elena Rybakina beat Laura Siegemund 6-3, 6-1. Read: Australian Open lookahead: Djokovic returns after COVID ban “Alexander Zverev has withdrawn from the United Cup due to a bicep strain,” organizers said. “Daniel Masur will take his place for Team Germany in today’s singles match against Kazakhstan.” Zverev has not won a Grand Slam singles title, finishing as runner-up in the 2020 U.S. Open and the 2024 French Open. The Australian Open begins Jan. 12.

Serena Williams withdrew from an Australian Open tuneup tournament citing a right shoulder injury on Friday within hours of setting up a semifinal match against top-ranked Ash Barty.