Andy Murray’s participation in the US Open has been thrown into doubt by a hip injury
World number one Novak Djokovic won the ATP title in Rome and clinched the year-end world rankings ahead of Rafael Nadal for the record seventh time.
The 31-year-old Serb won the last eight games in a 6-3 6-4 victory over Martin Klizan to claim the trophy on Sunday.
Djokovic ended the year with 10 titles, a 65-4 winning record and 95 matches.
Nadal, 30, took over top spot from Djokovic at the end of 2015 but suffered a dip in form in the second half of the year.
Andy Murray is absent from the ATP World Tour Finals in London
The Spaniard slumped to defeat by Djokovic in the quarter-finals of the French Open and slipped to third in the rankings in the final two months of the year.
Murray, meanwhile, sustained a hip injury earlier this month that will see him miss the US Open beginning on 31 August.
It leaves the Scot short of full match fitness and, with three Grand Slam titles this year, he trails Djokovic in the rankings.
Djokovic retains his 1,135 ranking points and goes back-to-back by keeping his year-end No. 1 ranking for the first time since 2011.