Alexander Zverev moved through at the Rogers Cup, while Marin Cilic also claimed a straight-sets win on Tuesday.
A former champion at the ATP 1000 event, Zverev was tested before getting past Cameron Norrie in the second round in Montreal.
The German was one of five seeds to win as only one – David Goffin – was beaten, while Nick Kyrgios also made an early exit.
ZVEREV PUSHES INTO LAST 16
Zverev, the third seed, saved a set point in the first before overcoming Norrie 7-6 (7-4) 6-4.
The 2017 champion served 10 aces but was tested by Norrie, saving all six break points he faced.
Zverev will face Nikoloz Basilashvili in the third round after the 13th seed edged Jan-Lennard Struff 2-6 6-2 6-3 in the day's only other second-round match.
GOOD DAY FOR SEEDS
Cilic, Borna Coric and John Isner joined Zverev and Basilashvili with wins as the trio moved into the second round.
The 14th seed, Cilic is starting to find some form and was too good for qualifier Bradley Klahn 6-3 7-6 (9-7).
His fellow Croatian Coric saved two match points before edging past Peter Gojowczyk 2-6 6-1 7-6 (7-2).
Isner was also pushed, but served 26 aces in a 3-6 6-3 7-6 (8-6) win over Australian Jordan Thompson.
Meanwhile, coming off a win at the Citi Open, Kyrgios made a first-round exit, losing to Kyle Edmund 6-3 6-4 and Goffin went down to Guido Pella 6-4 7-6 (7-4).
MURRAY, LOPEZ COMBINE FOR WIN
Wildcards in the doubles, Andy Murray and Feliciano Lopez battled through their opener, upsetting second seeds Lukasz Kubot and Marcelo Melo 6-7 (5-7) 6-3 11-9.
Their win – during which they saved a match point – included a bizarre moment when Lopez, with the ball flying well wide, caught it with his racquet before it bounced, losing the point.