Denis Shapovalov eased into the last 16 at the Winston-Salem Open, while Andrey Rublev claimed two wins on Tuesday.
Shapovalov was too good for Tennys Sandgren – who eliminated Andy Murray at the ATP 250 event – in a 6-2 6-4 second-round victory in North Carolina.
The Canadian second seed made it two straight-sets wins in as many meetings with Sandgren, advancing in one hour, 16 minutes.
Shapovalov will meet Miomir Kecmanovic, who got past Alexei Popyrin 7-6 (7-5) 6-3.
Russian Rublev, who beat Roger Federer last week in Cincinnati, posted a 6-4 6-2 first-round win over Italian Thomas Fabbiano and then beat Spanish ninth seed Albert Ramos-Vinolas 6-7 (5-7) 6-3 6-1.
The 21-year-old's wins came as the tournament played catch up after a rain-hit Monday.
Rublev will face Sam Querrey after the American sixth seed and 2009 runner-up served 15 aces in a 6-3 7-5 victory over Roberto Carballes Baena.
John Millman, the Australian who last year pulled off a huge US Open shock by beating Federer in the fourth round, was given a workout by Italian Marco Cecchinato before pulling through a 6-7 (5-7) 6-4 6-3 winner.
Millman will face Robin Haase next after the 32-year-old Dutchman, who has nosedived from 50th to 154th in the rankings during a rough season, caused a shock by beating fourth seed Joao Sousa 4-6 6-3 6-4.
French top seed Benoit Paire fended off Indian Prajnesh Gunneswaran 6-3 7-5 to also reach the third round, while Norwegian Casper Ruud joined him when South African opponent Lloyd Harris retired after dropping the first set 6-1 in their contest.
Last year's runner-up Steve Johnson is also into the last 16, while Hubert Hurkacz ended the run of Lee Duck-hee, who made history on Monday by becoming the first deaf player to win a main-draw ATP Tour match.
Also moving through were Ugo Humbert, Pablo Carreno Busta, Lorenzo Sonego, Filip Krajinovic, Frances Tiafoe and Feliciano Lopez.