Novak Djokovic produced an immaculate presentation of game and defeated American giant John Isner 6-4 6-3, who was making his tournament debut.
Djokovic will now set his sights on Alexander Zverev in his second round-robin match, after the 21-year-old beat Croatia’s Marin Cilic 7-6 (7-5), 7-6 (7-1) to open his account in the Gustavo Kuerten group.
Djokovic lost only four points on his own serve in the first set and managed to read Isner’s towering delivery, pinging back returns to the baseline with monotonous regularity. The Serb missed early chances to break but pounced in the sixth game, belting a forehand return for a 4-2 lead.
Isner saved a set point at 5-3 down and banged down three consecutive aces to stay in the set but Djokovic calmly held to seize the opener. The writing was on the wall for the American when Djokovic broke serve at 3-3 in the second set. Two games later, Djokovic sealed victory with a crosscourt backhand winner.
Zverev took the first set against Cilic in a tie-break after the Croat had chances to take a 4-0 and 5-1 lead. Cilic let the set slip from his grasp, and his German opponent took the breaker with a sublime backhand pass.