Former finalist Andrey Rublev began his Hamburg European Open campaign by defeating American qualifier Tennys Sandgren 6-3, 6-3 on Monday. The fifth-seeded Russian converted 90% of his first-service points, losing just three from 29.
Rublev, who lost to Nikoloz Basilashvili in last years final, next faces another American qualifier, Tommy Paul, who defeated Kevin Anderson of South Africa 6-4, 0-6, 6-4.
Also, 2011 champion Gilles Simon lost to Jiri Vesely 7-5, 6-2, and Pablo Cuevas defeated Taylor Fritz, another American, 6-4, 6-2.
Daniil Medvedev and Stefanos Tsitsipas are the top seeds at the clay-court tournament.