"I've been playing really good tennis lately and I'm just trying to keep that up," said four-time Grand Slam champion Alcaraz, who has won four titles on the ATP Tour this year.

He will next play China's world number 560 Yibing Wu, while Sinner will face 37th-ranked Martin Etcheverry in the third round following the Argentine's 7-6 (7-5) 3-6 7-5 win over the Netherlands' Botic van de Zandschulp. At three hours and 43 minutes, it was the longest match in the tournament's history.

Elsewhere, Russian sixth seed Andrey Rublev fell to a 6-7 (7-9) 6-4 6-3 defeat by Czech Republic's Jakub Mensik.

Novak Djokovic will be in action later on Saturday, against 20-year-old American Alex Michelsen, as the four-time Shanghai Masters winner aims for his 100th tour-level title.