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.
Switzerland's Roger Federer, 38, also reached the quarter-finals with a 7-6 (9-7) 6-4 win over Belgium's David Goffin.
Goffin could not convert any of five set points in the opener.
Federer, who won the Shanghai title in 2014 and 2017, will take on German fifth seed Alexander Zverev in the last eight, while Djokovic faces Greek sixth seed Stefanos Tsitsipas.