The Australian summer of tennis has been clouded with further uncertainty after up to 600 tennis players, officials and support staff were required to isolate until they return a negative test for Covid-19 following the news that a worker at an Australian Open quarantine hotel had tested positive for the virus. Tennis Australia consequently announced that all matches scheduled for Thursday at the warm-up tournaments have been postponed until Friday. The infected person, a 26-year-old man, had been working at the Grand Hyatt Hotel during the players’ time there and his most recent shift was on 29 January. After testing negative on a test administered that day, he developed symptoms and returned a positive test on Wednesday. Players who stayed at the Grand Hyatt, which includes highly ranked players, are considered casual contacts and must quarantine until their test results are known. Although the full extent of the situation will not be known until all results are back, the effect on warm-up tournaments is already notable. There are six tournaments in progress during a manic lead-up week at Melbourne Park and 62 matches were scheduled to be played on Thursday. With the Australian Open due to start on Monday, the tournaments were already tightly scheduled with little room for flexibility. Tennis Australia will now have to assess how to safely complete those events and allow players sufficient rest before the major begins. More complications may also further affect public opinion over the first grand slam of the year, which had already suffered following criticism some players received upon arrival in Australia. Daniel Andrews, Victoria’s premier, held a news conference on Wednesday to announce the case and urged those with symptoms in Melbourne to get tested. Andrews further noted that, at that moment, there were no disruptions to the Australian Open itself. He said: “They will be isolating until they get a negative test and that work will be done tomorrow so it might have an impact on tomorrow’s play in the lead-up event, but at this stage there’s no impact to the tournament proper. “That’s important to us, but the issue we’re most focused on is much broader. That’s about public health and public safety and that’s why we’ve really pounced on this.” On Wednesday, the court of arbitration for sport ruled on one of the unresolved incidents from the Australian Open as Dayana Yastremska lost her appeal to lift her provisional suspension after her positive doping test. Ukraine’s Yastremska, ranked No 29 in the world and considered one of the most promising young players on the women’s tour, tested positive for a metabolite of mesterolone, a synthetic testosterone, in a urine sample from an out-of-competition doping test on 24 November. Despite the positive test, Yastremska travelled to Melbourne on one of the charter flights funded by Tennis Australia, where she appealed against her suspension to the independent tribunal. The 20-year-old was on a contaminated flight from Abu Dhabi, meaning she was confined to her room for two weeks, but is now forbidden from competing in the Australian Open or even entering the Melbourne Park grounds. In Wednesday’s action, Naomi Osaka withstood an impressive performance from Britain’s Katie Boulter, who had reached the third round of the Gippsland Trophy with a strong win over Coco Gauff. Osaka recovered from a set down to defeat Boulter 3-6, 6-3, 6-1, ending the match by winning eight of the final nine games. Serena Williams was a victor in the Yara Valley Classic, producing a strong performance to see off Tsvetana Pironkova 6-1, 6-4. The world No 1 Ashleigh Barty continued to clean off her rust in the same event after her 11-month layoff, defeating Marie Bouzkova 6-0, 4-6, 6-3. In the ATP Cup, Russia and Italy advanced to the semi-finals after group stage victories over Japan and France respectively. While world No 1 Novak Djokovic will be in action again when play returns, Rafael Nadal continues to treat his lower back issues. After playing no part in Spain’s opening win over Australia, he signalled that he would not compete against Greece when it was still scheduled for Wednesday. However, he is healthy enough to continue training in Melbourne.