World number one Novak Djokovic produced another high-quality display to ease past American John Isner in the Shanghai Masters third round.

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.

He faces Greek sixth seed Stefanos Tsitsipas or Pole Hubert Hurkacz next.

"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.

Those losses came against Spanish world number two Rafael Nadal, who is not playing in Shanghai, in the US Open final last month and the Rogers Cup final in August.

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.