Andrey Rublev stayed on course for a quarterfinal match against ATP Cup-winning teammate Daniil Medvedev with a 7-5, 6-2, 6-3 third-round win over 39-year-old Feliciano Lopez.
Rublev and Medevedev both went unbeaten in the 12-team ATP Cup last week to clinch the title for Russia.
The seventh-seeded Rublev will meet Casper Ruud of Norway in the fourth round.
No. 5 seed Stefanos Tsitsipas beat Mikael Ymer of Sweden 6-4, 6-1, 6-1 in the third round. It was a much more straight-forward outing than his five-set marathon against Thanasi Kokkinakis in the second round.