Serb Djokovic, 32, did not face a break point as he won 7-5 6-3 against the big-serving 16th seed.
Defending champion Djokovic, who won the Japan Open last week, has not dropped a set in seven matches since injury forced him out of the US Open.
“I’m very happy with the way I am playing. This is one of the best serving matches I’ve played,” said Djokovic, who won 85% of his service points.
Russian third seed Daniil Medvedev saved five set points in the first set before squeezing past Canadian qualifier Vasek Pospisil.
The US Open runner-up, who won the St Petersburg Open last week, earned a 7-6 (9-7) 7-5 victory to extend his record to two defeats in his past 24 matches.
Medvedev, 23, will play 10th seed Fabio Fognini in the last eight after the 32-year-old Italian beat Russian seventh seed Karen Khachanov 6-3 6-5.
Italian 11th seed Marco Berrettini progressed with a 7-6 (7-5) 6-4 win over Spain’s Roberto Bautista Agut, boosting his chances to qualify for the season-ending ATP Finals in London next month.