Andy Murray and Novak Djokovic dropped outside the ATP top 10 for the first time in years in the latest rankings released on Monday. The 30-year-old Murray plummeted from third to 16th after not playing since July with a hip injury. The Scot's last appearance outside the top 10 was in October 2014. The three-time Grand Slam winner last appeared on court at Wimbledon, losing in the quarter-finals to American Sam Querrey. Shortly after that he was nudged off the top of the world rankings by Rafael Nadal, who sealed the end-of-year top spot at the Paris Masters last week.
Murray is due to face world number two Roger Federer in a charity exhibition match in Glasgow on Tuesday before he starts his preparations for the Australian Open by playing in Brisbane.
Djokovic, struggling with an elbow injury, was also last seen in action in the Wimbledon quarter-finals when he retired against Tomas Berdych.
The 12-time Grand Slam winner ends the year in 12th, down five places, for his lowest ranking since March 2007.
Djokovic is hoping to make a comeback at the exhibition World Tennis Championship in Abu Dhabi next month.
American Jack Sock, who beat Filip Krajinovic 5-7, 6-4, 6-1 in the Paris Masters final on Sunday, climbs 13 rungs to ninth in the ATP chart.
Sock's exploit in the French capital earned him a ticket to the World Tour Finals next week.
Nadal's participation in the season-ending tournament in London is in doubt after the world number one and 16-time Grand Slam champion pulled out of Paris before his quarter-final with a knee injury.