The third-seeded Musetti converted five of six break points while knocking off Ymer. Musetti won 26 of 34 (76.5%) of his first-serve points.

Fourth-seeded Alexander Zverev (26) of Germany rolled to a 6-3, 6-0 victory over Slovakia's Alex Molcan (28), while Germany's Yannick Hanfmann (31) posted a 4-6, 6-2, 4-2 win when fifth-seeded Francisco Cerundolo (24) of Argentina retired.

Number seven seed Alejandro Davidovich Fokina (24) of Spain and number eight Miomir Kecmanovic (23) of Serbia also prevailed.

Others winning first-round matches were Chile's Cristian Garin (27), France's Arthur Fils (19), Germany's Maximilian Marterer (23), Slovakia's Jozef Kovalik (30) and China's Zhizhen Zhang (26).

Plava Laguna Croatia Open Umag

Zsombor Piros (23) recorded a solid 6-3, 6-4 victory over fifth-seeded Christopher O'Connell (29) in the first round at Umag on a day in which only two matches were completed due to rain.

Piros, from Hungary, won 30 of 39 (76.9%) of his first-serve points while upsetting the Australian. Piros saved all four of his break points.

Seventh-seeded Italian Matteo Arnaldi (22) registered a 6-3, 6-2 victory over qualifier Jesper de Jong (23) of the Netherlands. Arnaldi also won 76.9% (20 of 26) of his first-serve points.