Second seed Marin Cilic, the 2014 ABN-AMRO finalist, led a pair of fellow Croatians into the second round as he beat Denis Istomin 7-6 (7-5), 6-4 to leave the Uzbek winless after three losses in as many years at the event.
The 13th-ranked Cilic is coached by famed compatriot Goran Ivnisevic, who won the Rotteredam trophy two decades ago.
"It would be so great to win the title 20 years later in front of Goran," said former US Open champion Cilic.
"To win here would be a huge honour. but the tournament is tough. I can only go step by step, but I will be pushing myself hard to try and win it."
Cilic won in 90 minutes with 10 aces and never faced a break point to improve to 7-1 over Istomin.
"It was a tough, mental challenge," the winner said. "The first set was very close and the second was a mental battle. I was lucky to pull it through."
Countryman and qualifier Ivan Dodig, ranked 87th, delivered a 6-3, 7-6 (7-4) surprise to French seventh seed Benoit Paire, who has now lost four straight matches dating back a month to Auckland.
He fell victim to more than 50 unforced errors as the match-tough Dodig won in his third match point and claim revenge for a 2013 loss in Monte Carlo.
Croatia's Borna Coric snapped a three-match loss streak with an heroic performance as he saved 10 set points in the opening set to defeat Dutchman Thiemo de Bakker 7-6 (11/9), 4-6, 6-3.
"It was very close, At the end I was a bit lucky but also I was brave," Coric said. "It paid off at the end. On five of the set points I played very well - on the other five I got lucky," Coric said.
Jiri Vesely beat fellow Czech Lukas Rosol 6-4, 6-2.