Ivan Dodig of Croatia had nine aces as he beat fifth-seeded Andreas Haider-Maurer of Austria 7-5, 6-3 to reach second round of the inaugural Istanbul Open on Tuesday.
Dodig saved six of the seven break points he faced and broke Haider-Maurer's serve four times.
In other matches, sixth-seeded Kazakh Mikhail Kukushkin saved seven of eight break-point chances on his serve as he beat countryman Aleksandr Nedovyesov 6-3, 6-4; and No. 8 Diego Schwartzman of Argentina broke qualifier Blaz Kavcic's serve seven times in a 6-2, 6-1 win.
Second-ranked Roger Federer is in second-round action on Wednesday, where the Swiss star looks to improve to 15-0 in career matches against Finland's Jarkko Nieminen.
Nieminen advanced with a 6-3, 6-4 win against Turkey's Marsel Ilhan.
In other first-round matches, there were wins for Spaniard Daniel Gimeno-Traver, Russian Andrey Rublev, Austrian Jurgen Melzer, Uzbekistan's Denis Istomin, Russian Teymuraz Gabashvili and Dusan Lajovic of Serbia.
Melzer was 5-2 up against Steve Darcis when the Belgian player retired with a wrist injury.