Top seed Philipp Kohlschreiber was dumped out of the bet-at-home Cup Kitzbuhel after being beaten 6-3 7-5 by David Goffin in the second round.
Kohlschreiber was playing one of six second-round matches which took place on Thursday following their postponement from the previous day due to heavy rain.
Belgian wildcard Goffin claimed the big scalp of the day before moving on to the semi-finals with a 6-2 6-1 win against Paolo Lorenzi.
Third seed Lukas Rosol also suffered a shock exit as he was defeated 6-3 4-6 6-3 by Maximo Gonzalez in the quarter-finals. Gonzalez will face Goffin in the last four.
There was better news for second seed and defending champion Marcel Granollers of Spain, who claimed a 6-3 6-4 triumph over Argentina's Diego Schwartzman to advance.
Last year's beaten finalist Juan Monaco remains on course to go one better this time around after he dispatched seventh seed Jarkko Nieminen 6-3 6-4.
Home favourite Dominic Thiem, seeded fifth, overcame a tough second set to reach the quarter-finals as he moved past Jiri Vesely of the Czech Republic 6-3 7-6 (7-3).
Former champion Andreas Seppi, seeded fourth this year, was handed a walkover when his opponent Pere Riba withdrew before their tie with a viral infection.