Guillermo Garcia-Lopez blew away ATP Tour newcomer Lorenzo Giustino to book his place in the second round of the Nastase Tiriac Trophy with a 6-2 6-0 victory.
Qualifier Giustino was playing his maiden match on the Tour, but mustered just five points on his opponent's serve as he was comfortably beaten.
Garcia-Lopez, who won the Zagreb Indoors in February, will now meet Marcos Baghdatis - a 6-4 6-2 victor over Steve Darcis.
Andreas Haider-Maurer looked to have blown his chances of progression before bouncing back to claim a 7-5 0-6 6-4 victory against Ivan Dodig.
He will now face eighth seed Simone Bolelli after the Italian came through his first-round clash with Andrey Golubev 7-6 (7-3) 6-4.
Top seed Gilles Simon awaits wildcard Janko Tipsarevic following the latter's 6-4 6-3 win over Thomas Fabbiano, while Dusan Lajovic saw off qualifier Jurgen Zopp 7-5 6-1.
World number 289 Nikola Mektic caused the upset of the day by beating 65th-ranked Denis Istomin 6-3 6-4, but seventh seed Jiri Vesely had no such problems, beating Diego Schwartzman 6-3 7-6 (11-9).