American Denis Kudla serves during the men's singles third round match against Novak Djokovic of Serbia at the 2019 US Open tennis championships in New York, the United States, Aug. 30, 2019. (Xinhua/Li Muzi) U.S. tennis player Denis Kudla tested positive for COVID-19 at the Australian Open qualifiers while his Moroccan Elliot Benchetrit suffered a "double whammy". SYDNEY, Jan. 12 (Xinhua) U.S. tennis player Denis Kudla tested positive for.