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.