Defending champion Lorenzo Musetti cruised to a 6-4, 6-1 victory over Sweden's Elias Ymer in the first round of the Hamburg European Open in Germany.
The third-seeded Musetti converted five of six break points while knocking off Ymer. Musetti won 26 of 34 (76.5 percent) of his first-serve points.
Fourth-seeded Alexander Zverev of Germany rolled to a 6-3, 6-0 victory over Slovakia's Alex Molcan, while Germany's Yannick Hanfmann posted a 4-6, 6-2, 4-2 win when fifth-seeded Francisco Cerundolo of Argentina retired. No. 7 seed Alejandro Davidovich Fokina of Spain and No. 8 Miomir Kecmanovic of Serbia also prevailed.
Others winning first-round matches were Chile's Cristian Garin, France's Arthur Fils, Germany's Maximilian Marterer, Slovakia's Jozef Kovalik and China's Zhizhen Zhang.
Plava Laguna Croatia Open Umag
Zsombor Piros recorded a solid 6-3, 6-4 victory over fifth-seeded Christopher O'Connell 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 percent) of his first-serve points while upsetting the Australian. Piros saved all four of his break points.
Seventh-seeded Italian Matteo Arnaldi registered a 6-3, 6-2 victory over qualifier Jesper de Jong of the Netherlands. Arnaldi also won 76.9 percent (20 of 26) of his first-serve points.
Six-time event champion John Isner didn't make it out of the first round this year in Atlanta, falling 3-6, 7-6 (4), 7-6 (3) to Germany's Dominik Koepfer.
Neither player broke serve in the final two sets. Isner had the lone break point of the second set at 1-2 and Koepfer had the only break point of the third set at 2-3, but neither could convert.
In a matchup of two Georgia natives and Georgia Tech alumni, fifth-seeded Christopher Eubanks beat Andres Martin 6-2, 6-4. Eubanks is looking to build on his quarterfinal result at Wimbledon.
Other first-round winners were seventh-seeded Ugo Humbert of France, Japan's Kei Nishikori, China's Yibing Wu and Juncheng Shang and U.S. players Brandon Nakashima and Maxime Cressy.
--Field Level Media