Australian Open tennis players have begun to leave hotel quarantine after completing their 14-day isolation, about a week before the event starts.By Sunday, about 500 players will have been released from hotels in Melbourne and Adelaide, organisers said. High-profile stars Novak Djokovic, Rafael Nadal and Serena Williams were among those allowed out on Friday. Players have quarantined because of the Australian government's Covid-19 rules for anyone entering the country. In early January, more than 1,700 players, staff and others tied to the Grand