Defending champion Novak Djokovic made a strong start to his Shanghai Masters campaign with a straight-sets victory over Denis Shapovalov.
Djokovic arrived in China having put worries about a shoulder problem behind him by winning the ATP title in Tokyo last week and he was in excellent form in a 6-3 6-3 win against Shapovalov to reach the third round.
There he will play 16th seed John Isner, who was a 7-5 6-3 winner over Frenchman Lucas Pouille.
The upturns in form for Alexander Zverev and Stefanos Tsitsipas continued, with the two men posting near identical results.
Tsitsipas had previously described Felix Auger-Aliassime as the toughest opponent he had ever faced but he finally got a first win over the Canadian teenager, beating him 7-6 (3) 7-6 (3).
Zverev, meanwhile, continued his pursuit of a qualifying spot for the ATP Finals with a 7-6 (13) 7-6 (3) victory over Jeremy Chardy.
Fourth seed Dominic Thiem continued his winning run after lifting the trophy in Beijing last week with a 7-6 (3) 6-3 victory over Pablo Carreno Busta.
On a very good day for the seeds, there were also wins for Karen Khachanov, Roberto Bautista Agut, Matteo Berrettini, Andrey Rublev and David Goffin, who will take on Roger Federer in the third round.