Andy Murray says he is determined to keep improving so he remains world number one after winning BBC Sports Personality of the Year for a record third time.
Murray collected the main award from Miami where he is training for 2017.
"It's possible everything doesn't go perfectly next year and I need to be prepared," the 29-year-old said.
"I know staying at the top is a really difficult thing to do. I'm not taking anything for granted."
He added: "I'm sure Novak [Djokovic] will be wanting to get back to the top spot but it's taken me so long to get here that I want to stay there as long as I can, and that's why I'm over here now.