Marco Chiudinelli upset German eighth seed Philipp Kohlschreiber to reach the second round of his hometown event in Basle.
The world number 73 came out on top after a two-hour, 15-minute tussle on Centre Court at the Davidoff Swiss Indoors, to set up a clash with compatriot Michael Lammer.
The first set saw the players pass up seven break points between them before Chiudinelli prevailed 7-5 in a tie-break.
Kohlschreiber levelled but a decisive late break saw! the underdog complete a 7-6 (7-5) 3-6 7-5 victory.
Lammer, meanwhile, battled past Austria's Daniel Koellerer, winning 3-6 6-2 7-5.
Second seed Novak Djokovic made easy progress, beating another German, Andreas Beck, 6-3 7-5.
The Serbian served 10 aces and broke serve three times in the one-hour, 27-minute clash and will next face Czech Jan Hernych, a 6-3 6-4 victor over Australia's Peter Luczak.
Finn Jarkko Nieminen overcame a 74-place gap in the world rankings to rout Julian Benneteau 7-5 6-2, his second win in as many meetings with the Frenchman.
Serbia's Viktor Troicki came through 6-2 7-6 (7/5) against Benjamin Becker as the German contingent in action today all crashed out, and Russia's Evgeny Korolev came from behind to beat Simone Bolelli of Italy 3-6 7-6 (7/4) 6-2.
