Olympic champion Belinda Bencic has tested positive for Covid-19 after her trip to Abu Dhabi, describing her symptoms as "severe".
Bencic, 24, is the third player to test positive after travelling to the Mubadala World Tennis Championship.
Britain's US Open champion and the 2021 BBC Sports Personality of the Year winner Emma Raducanu withdrew before the start of the tournament.
Rafael Nadal revealed he had tested positive upon his return to Spain.
In a Twitter post, Switzerland's Bencic said: "Unfortunately and even though I am fully vaccinated, I recently tested positive for COVID-19.