Second-seeded Alex Bogomolov Jr. of Russia beat wild card Dino Marcan of Croatia 6-3, 6-1 to advance to the second round of the Zagreb Indoors on Tuesday.
Bogomolov, a quarterfinalist here last year, had little trouble with Marcan, who was making his debut on the ATP Tour.
In November, Bogomolov decided to play for the country of his birth, Russia, rather than the United States, where he has lived and trained since 1992.
Two-time finalist Michael Berrer of Germany defeated Marco Chiudinelli from Switzerland 7-6 (3), 6-1. Berrer next faces top-seeded Ivan Ljubicic.