Maximilian Kieffer birdied three of his last five holes to set the clubhouse target on day one of the Omega European Masters.
The German recently recorded his first top five of the season at the Nordea Masters and he brought that form to Crans-sur-Sierre Golf Club, carding a 64 to take a one-shot lead at six under.
Frenchman Julien Guerrier, Dane Søren Kjeldsen and England's Andy Sullivan were five under, a shot clear of Scot David Drysdale, Spaniard Nacho Elvira and South African pair Erik van Rooyen and Justin Walters.
Japan's Hideto Tanihara was also at four under after making four gains in the first seven holes of his opening round.
Kieffer has established himself as one of the most consistent players on Tour since graduating from the Challenge Tour in 2012, keeping his card every season since.
Sullivan made four birdies in a row from the 12th and then added another on the 17th to turn in 30 and jump into a two-shot lead.
Kjeldsen made birdies on the second, fifth, seventh and tenth and with Sullivan making a bogey on the fourth, the lead was shared.
Kieffer made gains on the fifth, seventh, eighth and 11th to make it a four-way tie but Kjeldsen got on the green at the par five 14th in two for a birdie of his own and the solo lead.
A Sullivan bogey on the sixth and a dropped shot from Kieffer on the 12th meant Kjeldsen led by two but he was soon reeled in.
Sullivan got up and down from the front of the driveable par four seventh and then did the same again on the par five ninth as he and Kjeldsen set the early clubhouse target.
Kieffer was not done, however, and he made the most of the back-to-back par fives at the 14th and 15th before birdieing the par three 16th to hit the front on his own.
Guerrier had started with a bogey on the tenth but he went birdie-eagle on the 14th and 15th and came home in 32 with birdies on the first, sixth and seventh.
Drysdale made a single bogey in his 66, while Elvira and Walters both dropped two shots, with the latter also making an eagle on the 15th.
Van Rooyen had more of a roller coaster of a round, closing with his seventh and eighth birdies of the day but also making four bogeys.
Belgian pair Thomas Detry and Thomas Pieters, Spaniard Pablo Larrazábal, French duo Alexander Levy and Matthieu Pavon, England's Aaron Rai and South African Charl Schwartzel were all at three under.
Last week's winner Matt Wallace and local favourite Benjamin Rusch were in the group at two under, a shot ahead of defending champion Matthew Fitzpatrick.
