Pablo Cuevas was the biggest casualty on a day of second-round upsets at the Generali Open as the top seed was toppled by the unfancied Sebastian Ofner in three sets.
Ranked some 130 places above the Austrian wildcard, Cuevas initially recovered from losing the opening set, but eventually slumped to a 6-3 2-6 7-6 (7-3) defeat to the world number 157.
Ofner impressively held his nerve despite a delay for rain and he stated after the match: "I'm happy that I stayed focused during the tie-break and I played well.
"It's a great feeling to be in the quarters and of course it's very special to play in front of my home crowd."
Cuevas was one of six seeds to exit the clay-court tournament on Wednesday, with defending champion Paolo Lorenzi (3) beaten 6-7 (5-7) 6-4 6-1 by Joao Sousa and Gilles Simon (4) losing 6-4 6-4 to Dusan Lajovic.
Jan-Lennard Struff (6), Jiri Vesely (7) and Horacio Zeballos (8) also bit the dust to Thomaz Bellucci, Philipp Kohlschreiber and Renzo Olivo respectively - the latter representing the next challenge for Ofner.
Fabio Fognini (2), victor of last week's Swiss Open, was the only seed to survive, with the Italian accounting for Miljan Zekic in a 6-4 6-4 win, while there was more home success for Gerald Melzer against Santiago Giraldo.