Nick Kyrgios won his all-Aussie showdown against Alex de Minaur, while Felix Auger-Aliassime was impressive against Cameron Norrie.
Jack Draper will play in his first Masters 1000 quarter-final after his opponent Gael Monfils retired injured midway through their last-16 match at the Canadian Open on Thursday.
Draper reached his first Masters 1000 quarter-final one day after defeating Stefanos Tsitsipas.
After 18 holes at TPC Southwind J.J. Spaun and Kim Si-woo lead the pack at eight under, while favourite Rory McIlroy is at even par.