MELBOURNE, Australia — Novak Djokovic was back in immigration detention Saturday after his legal challenge to avoid being deported from Australia for being unvaccinated for COVID-19 was moved to higher court. A Federal Court hearing has been scheduled for Sunday, a day before the men’s No. 1-ranked tennis player and nine-time Australian Open champion was due to begin his title defense at the first Grand Slam tennis tournament of the year. Djokovic and his lawyers had a morning meeting with immigration officials and, by mid-afternoon, Australian media reported the tennis star was taken back into detention.