Rotterdam Open top seed Stefanos Tsitsipas and defending champion Felix Auger-Aliassime were joined by Daniil Medvedev in progressing through their first-round ties.
Auger-Aliassime won his first Tour-level title at the event last year and went from strength to strength in 2022, winning another three singles trophies.
The world number eight, seeded third, started his title defence with a convincing 6-2 6-3 defeat of Italy's Lorenzo Sonego on Tuesday.
"Of course, I was hoping to win and get through, but 6-2, 6-3 is a great performance against a player that is tricky like he is... it's a great way to start the week," said Auger-Aliassime, who needed just 82 minutes to clinch victory and set up a last-16 meeting with qualifier Gregoire Barrere.
The Canadian is relishing his title defence, and feels he is a stronger competitor than this time last year in a warning shot to his rivals.
He added: "Last year was an amazing year, but this year is a different one. I think I'm a better player overall.
"Of course, the best thing I can do compared to last year is win again, so hopefully I can do that. The draw is really strong, but I'm confident if I can keep playing the way I did today I'll get my chances and then we'll see."
Auger-Aliassime might be the reigning champion, but world number three Tsitsipas is the favourite.
Emil Ruusuvuori was no match for Australian Open runner-up, who prevailed 7-5 6-1 and has a 13-1 record for the season.
"The process that you get to repeat these things over and over again, it gives you tremendous understanding of how things actually work," Tsitsipas said.
"I think being able to get in these moments more and more often on the Tour helps you understand, makes you wiser when you're trying to deal with all these problems."
Tsitsipas, who could face Open Sud de France champion Jannik Sinner in the next round, ensured there would be no curse of the top seed in Rotterdam, where the favourite had lost their first match in two of the last three editions.
On both occasions (2020 and 2021), that was Medvedev, but the former world number one fought from a set down to beat Alejandro Davidovich Fokina 4-6 6-2 6-2.
World number 10 Hubert Hurkacz also had to battle against a Spaniard in the form of Roberto Bautista Agut. The fifth seed needed three hours to win 7-5 6-7 (7-9) 7-6 (7-4) and tee up an encounter with Grigor Dimitrov.
Alexander Zverev defeated Soonwoo Kwon in straight sets to book his progress, while Gijs Brouwer got the better of Marc-Andrea Huesler.