Britain's Andy Murray is still troubled by a groin injury and has not travelled to Miami for his scheduled December training block.
The former world number one was affected by the problem at last month's Davis Cup Finals.
He is still able to train off court and is expected to start playing again within the next seven days.
Murray plans to represent Britain in the inaugural ATP Cup which starts on 3 January.
He is then expected to compete at the Australian Open in Melbourne from 30 January.
The three-time Grand Slam winner played just one match during Britain's run to the Davis Cup semi-finals.
In October, he won his first singles title since career-saving hip surgery in January, beating Stan Wawrinka at the European Open.