Novak Djokovic defeated Filip Krajinovic in the first round in Vienna on Tuesday to edge closer to Pete Sampras's all-time record of ending the year as world number one on six occasions.

Djokovic beat compatriot Krajinovic 7-6 (8/6), 6-3 and needs to win his next match in Austria against Borna Coric to ensure he equals the achievement of his childhood idol.

The 33-year-old Serb has been the top-ranked player at the end of a season five times: in 2011, 2012, 2014, 2015 and 2018.

He shares that mark with career rivals Roger Federer and Rafael Nadal.

Sampras achieved the feat six years in succession between 1993 and 1998.