Novak Djokovic and Serena Williams have been named the men's and women's world champions for 2015 by the International Tennis Federation.
Djokovic 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 Open.
Williams also narrowly missed a calendar‑year grand slam, winning the Australian, French and Wimbledon and reaching the US Open semi‑final.
