LONDON (Reuters) - World number one Novak Djokovic says he still does not know whether the ATP Cup will take place in Australia in January.Djokovic led Serbia to the title in the first edition of the 24-nation tournament this year before going on to win the Australian Open for a record-extending eighth time. Tennis Australia boss Craig Tiley has said all the Australian Open warm-up events, including the ATP Cup, will be held in the state of Victoria next year in light of the COVID-19 pandemic, although state premier Daniel Andrews said that is “not a done deal”. Players will have to undergo a two-week quarantine period before being cleared to play in Australia ahead of the Melbourne Grand Slam, posing logistical problems as they would have to arrive in the country far earlier than usual. Asked about the situation after his 6-3 6-2 win over Diego Schwartzman in his first match at the ATP Finals on Monday, Djokovic said it was challenging.