Andy Murray has admitted that it will be "very tough" to hold down his current world number one ranking and expects Novak Djokovic to remain his biggest threat.
The 29-year-old enjoyed a hugely successful 2016 as he defended his Olympic title, won a second Wimbledon crown and prevailed at the ATP World Tour Finals to seal top spot.
Murray believes that 12-time Grand Slam winner Djokovic remains a real force, however, and is fully aware that his tag of being the world's best player is at risk heading into his first tournament of the year at the Qatar Open.
"In terms of the number one ranking, Novak would be [my biggest threat]," he is quoted as saying by Sky Sports News. "I had a great sort of four, five months at the end of last year and I still only got to No 1 by one match, basically at the end of the year, so I know it will be very tough to stay there."
Murray faces Jeremy Chardy is his Qatar opener on Tuesday and could take on Djokovic in the final should the seedings go to plan.
