Kitzbuehel - Pablo Andujar has beaten Jurgen Melzer 6-3, 6-4 at the Kitzbuehel Cup on Tuesday, two days after earning his third career title in Gstaad.
The 44th-ranked Spaniard broke the Austrian's first service game to win the opening set, and saved three break points while 2-1 down in the second before adding another break.
Melzer returned from a toe injury and played his first match since losing to Jo-Wilfried Tsonga in the first round at Wimbledon.
Andujar will face Paolo Lorenzi of Italy in the second round. Lorenzi defeated two-time former champion Robin Haase 6-2, 6-3.
The sixth-seeded Dutchman, who won the event in 2011 and '12, dropped serve early in both sets and failed to break Lorenzi's serve.
Last year's finalist, Juan Monaco, overcame a slow start to defeat Andrey Golubev of Kazakhstan 0-6, 6-2, 6-1.
The 81st-ranked Argentine won just five points on serve in the opener and trailed 6-0, 1-4 when the match was interrupted for an hour by rain.
Monaco will next play No. 7 Jarkko Nieminen of Finland, who beat Teymuraz Gabashvili of Russia 6-4, 6-4.
Results from the second day of the ATP Kitzbuehel Cup on Tuesday (x denotes seeded player):
David Goffin (BEL) bt Kenny De Schepper (FRA) 6-2, 6-4
Jarkko Nieminen (FIN x7) bt Teimuraz Gabashvili (RUS) 6-4, 6-4
Paolo Lorenzi (ITA) bt Robin Haase (NED x6) 6-2, 6-3
Juan Monaco (ARG) bt Andrey Golubev (KAZ) 0-6, 6-2, 6-1
Pablo Andjar (ESP) bt Jurgen Melzer (AUT) 6-3, 6-4
Diego Schwartzman (ARG) bt Alexander Zverev (GER) 6-1, 6-0