Novak Djokovic broke the single-season tennis record.
The ATP World Tour Masters 1000 ( previously known as the ATP Championship Series , Single-Week , ATP Super 9 , Tennis Masters Series , and ATP Masters Series ) is the third highest tier of men 's tennis tournament after the four Grand Slam tournaments and ATP World Tour Finals . Novak Djokovic . Djokovic 's records include breaking the single-season record with six masters titles in 2015 , winning 31 consecutive ATP World Tour Masters 1000 series matches , playing in the finals at all nine ATP Masters 1000 tournaments ( shared with Roger Federer and Nadal , and being the only player to win eight of the nine events ( and at least twice ) .