Andy Murray and Serena Williams are set to play at the Australian Open in January, according to tournament director Craig Tiley.
British number one Murray, 30, has not played since July when a hip injury hampered him in a quarter-final defeat at Wimbledon, while Williams, 36, gave birth to her first child in September.
The pair could be joined by Novak Djokovic and Stan Wawrinka, says Tiley.
"All the top players will be back in Melbourne," he said.
Former world number one Djokovic has been sidelined since suffering an elbow injury at Wimbledon, while Wawrinka and Nishikori have been out since the summer with respective knee and wrist problems.