PARIS—Novak Djokovic celebrated his return to the summit of world tennis with a stroll into the quarter-finals at the Paris Masters as outclassed Damir Dzumhur had to retire with injury in the second set of their third round clash on Thursday.
The Serb, who learned on Nov. 1, that he would be back as world number one next week following Rafa Nadal’s withdrawal from the tournament through injury, was leading 6-1 2-1 when the Bosnian submitted to a back problem that had flared up in the first set.
