Den Bosch (Netherlands), June 15 : Italy's Jannik Sinner passed his first test in the 2023 grass-court season with flying colours, beating Alexander Bublik in straight sets at the Libema Open here. The big-serving Bublik posed a big test for Sinner first up in his grass court season opener but the second seed nullified the threat for a 6-4, 6-2 victory at the ATP 250 event in 's-Hertogenbosch. Sinner managed to convert three of his 12 break points to earn an 84-minute win in his second-round clash with Bublik, who is a two-time ATP Tour finalist on grass. Sinner is now 11-0 in opening matches at tour-level events this season. The 21-year-old is relatively inexperienced on grass, on which he holds a 5-5 record, but the 2022 Wimbledon quarterfinalist again demonstrated how effective his ferocious groundstrokes can be on the surface with a classy performance against Bublik. Sinner's quarterfinal opponent will be Emil Ruusuvuori after the Finn notched a hard-earned 6-2, 6-7(6), 6-4 triumph against seventh seed Ugo Humbert. It will be Ruusuvuori's second tour-level quarter-final of the season, with Sinner his opponent in both. The Italian prevailed in straight sets in the pair's last-eight clash in Miami in March. In other matches on Wednesday, American Mackenzie McDonald stunned third-seed Borna Coric 6-4, 6-3 while 11th-seeded Australian Rinky Hijikata defeated Marc-Andrea Huesler of Switzerland 2-6, 7-5, 6-3. /IANS