Dominic Thiem outlasted qualifier Sebastian Ofner 6-2, 3-6, 6-3 to advance to the quarterfinals of the Generali Open on Wednesday.
The 2020 U.S. Open champion was a break down twice in the deciding set and saved two break points when he was serving for the match before prevailing over his fellow Austrian.
The 28-year-old Thiem, who came back in March from a long-term wrist injury, has now reached at least the quarterfinals in the last three tournaments he played, including Bastad and Gstaad.
The former world No. 3, who won the clay-court tournament in 2019, will face next Yannick Hanfmann after the German beat Ivan Gakhov 6-3, 6-7 (5), 6-4.
Three seeded Spanish players made the last eight after winning their second-round matches in straight sets.
Third-seeded Roberto Bautista Agut eliminated Austrian wild-card entry Jurij Rodionov 6-1, 6-4, fifth-seeded Albert Ramos-Vinolas defeated Juan Pablo Varillas of Peru 6-3, 6-4 and seventh-seeded Pedro Martinez beat Federico Coria of Argentina 6-4, 6-3.
Two other seeded players are out.
Fourth-seeded Aslan Karatsev of Russia was ousted by Dusan Lajovic of Serbia 7-5, 6-3 and Czech player Jiri Lehecka upset eighth-seeded Joao Sousa of Portugal 7-6 (6), 1-6, 6-3.
Another Spaniard, unseeded Pablo Andujar, lost to Austrian wild-card entry Filip Misolic 6-4, 6-0.