Former world number one Novak Djokovic says his long-awaited comeback is in doubt because of an elbow injury.
The 12-time Grand Slam winner has not played since the Wimbledon quarter-final against Tomas Berdych in July.
Djokovic was expected to make his comeback at this month's Mubadala World Tennis Championship.
He said: "This might affect the start of the season and the tournament plan, but the decision will be made in the following days."
More to follow.