Qualifier Marius Copil had nine aces as he upset sixth-seeded Joao Sousa of Portugal 4-6 6-3 6-3 in the first round of the European Open.
The 198-ranked Romanian also beat the 33rd-ranked Sousa on indoor hard courts in Stockholm, Sweden two years ago.
Copil converted his four break-point chances on Tuesday and next faces Steve Darcis of Belgium or Frenchman Benoit Paire.
In other first-round action, Argentine Diego Schwartzman downed seventh-seeded Nicolas Mahut of France 7-6 (7-2) 7-5 - with both regularly dropping their serve - and German Jan-Lennard Struff had 11 aces in a 6-7 (7-3) 6-3 6-0 win over Russian Mikhail Youzhny.
Struff and Youzhny conceded a whopping 39 break-point chances between them, with Youzhny dropping his serve eight times.
Slovak qualifier Jozef Kovalik downed Spaniard Guillermo Garcia-Lopez 6-3 6-3 while Britain's Kyle Edmund beat Ukraine's Illya Marchenko 7-6 (9-7) 7-6 (7-5) to set up a second-round match against No.2 David Ferrer of Spain.
Also, Germany's Florian Mayer broke Spaniard Tommy Robredo's serve five times to go with seven aces in a 6-2 6-2 win.