Dec 13 (Reuters) - U.S. Open champion Emma Raducanu has tested positive for COVID-19 and will miss this week"s Mubadala World Tennis Championship exhibition event in Abu Dhabi, the 19-year-old Briton said on Monday. Raducanu, who became the first qualifier to win a major when she triumphed at Flushing Meadows in September, was due to face Olympics singles gold medallist Belinda Bencic at the Dec. 16-18 event. "I was very much looking forward to playing in front of the fans here in Abu Dhabi, but unfortunately after testing positive for COVID-19, I will have to postpone until the next opportunity," Raducanu said. "I"m isolating as per rules and hopefully will be able to get back soon." Organisers said that they are looking at "alternative top female competitors" to replace Raducanu at the event. Men"s world number six Rafa Nadal and last year"s U.S. Open winner Dominic Thiem are set to return from their injury layoffs in Abu Dhabi. Britain"s Andy Murray, Russian Andrey Rublev, Norway"s Casper Ruud and Canadian Denis Shapovalov will also participate in the event before the 2022 competitive season kicks off in Australia.