The Serbian has won his last three tournaments – two ATP 1000 events and a grand slam – and can climb to the top of the ATP rankings if he betters Rafael Nadal's performance this week.

Djokovic registered a 19th consecutive triumph despite a difficult first set, the tournament's most successful singles player initially performing some way below his brilliant best.

The in-form second seed broke early in fairly rudimentary fashion, before exerting himself to rescue three break points and maintain control of the first set.

Djokovic could not prevent the break back when Sousa piled on the pressure again, however, and the Portuguese was left frustrated with the chair umpire when the opportunity for a shock lead dissipated.

The opener instead fell in Djokovic's favour at the last and he worked hard to claim a swift advantage in the second, accelerating out of sight in an ultimately comprehensive victory.