Twice champion Roger Federer was far from his best but did enough to overcome David Goffin.
World number one Novak Djokovic produced a majestic display in a 7-5, 6-3 victory over American John Isner on Thursday to extend his winning streak in Asia and reach the Shanghai Masters quarter-finals.
Djokovic, who arrived in Shanghai after winning the Japan Open in Tokyo over the weekend without losing a set, did not drop serve in the 75-minute encounter and clinically took both of his break-point opportunities against the big-serving American.
Those breaks came in a commanding period where, at 5-5 in the opening set, the 16-times Grand Slam champion swung the momentum of the match his way by winning five games in a row.
"It's always a big challenge returning the serve of Isner," Djokovic said of his 6-foot-10-inch opponent. "He's got one of the biggest serves of all time. With that height, the serve is a huge weapon and huge advantage.
"I managed to read his serve and find a good position on the return at the end of the first set and also (at the) beginning of the second... I thought it was one of the best serving matches I had lately."
Djokovic, the defending champion, will next play Greek sixth seed Stefanos Tsitsipas who beat Poland's Hubert Hurkacz 7-5, 3-6, 7-6(5) in the only three-setter of the day.
Twice champion Roger Federer was far from his best but did enough to overcome David Goffin 7-6(7), 6-4. Federer committed 40 unforced errors but saved five set points in the opening set.
"I never really felt like I had the upper hand over David today, I thought he did a really good job. He was so much better than at the US Open," Federer said of his Belgian opponent who he beat in straight sets in last month's Grand Slam.
"I think he was very clear in his shot selection... He was super fast on his feet today which made it really hard for me to get my freebies and winners off the baseline because he was getting to all of them."
The Swiss second seed will be up against German fifth seed Alexander Zverev, who dispatched Andrey Rublev 6-0, 7-6(4) in 84 minutes.
Third-seed Daniil Medvedev also advanced with a 7-6(7), 7-5 victory over Canadian Vasek Pospisil while fourth-seed Dominic Thiem recorded a straightforward 6-3, 6-4 win over Georgian Nikoloz Basilashvili.
