Adrian Otaegui fired three successive birdies before the turn to take an early lead at the Lyoness Open powered by Sporthilfe Cashback Card.
The 23 year old Spaniard picked up shots at the seventh, eighth and ninth to head into the back nine on four under, one shot clear of the pack at Diamond Country Club.
Scotland's Scott Jamieson is among a group of five players a shot behind, after picking up a fifth birdie of the round on the 11th to go with dropped shots at the second and fifth.
Australia's David Bransdon is also a stroke off the lead after eagling the par five first and adding a birdie on the fourth.
Defending champion Chris Wood made a solid start to his title defence.
Starting on the back nine, the BMW PGA Championship winner picked up shots on the 12th and 15th to lie within two shots of Otaegui at the turn.
Playing partner, and home favourite, Bernd Wiesberger, is a shot further back after opening with eight pars and a birdie on 15.
