Novak Djokovic and Serena Williams were named men's and women's world champions for 2015 by the International Tennis Federation on Tuesday.
The Serb ended the year as men's world number one for the fourth time after taking three majors - the Australian, Wimbledon and US Open, as well as finishing runner-up to Stan Wawrinka in the French.
Williams also narrowly missed a calendar-year grand slam, winning the Australian, French and Wimbledon and reaching semi-final at US Open.
Martina Hingis, of Switzerland, and India's Sania Mirza were named women’s doubles world champions, with Jean-Julien Rojer, of the Netherlands, and Romania’s Horia Tecau taking the men's award.
Hingis thus became an ITF world champion again 15 years after being crowned singles champion.
Dalma Galfi, of Hungary, and USA’s Taylor Fritz were named ITF junior champions.