Romain Langasque fired a brilliant 63 to set the second-round clubhouse target on a morning of low scoring at the Omega European Masters.
The Frenchman made an eagle and five birdies as he moved to nine under, one shot clear of Alex Noren who also posted a bogey-free 63.
Andrew Johnston was then at seven under, with 18 players within four shots of the lead at Crans-sur-Sierre Golf Club.
Langasque burst onto the scene when he won the 2015 Amateur Championship and he then secured a top 40 finish at the Masters Tournament. Since then he has surged to the top of the Challenge Tour rankings but was playing just his fifth European Tour event this week.
He looked very comfortable in the Alps, though, with an eagle on the par five 14th sandwiched by birdies on the 11th and 17th as he turned in 31.
A glorious approach to six feet on the fifth moved him ahead on his own before further gains on the drivable seventh and the par five ninth.
Playing partner Johnston had hit the front with birdies on the 14th and 15th but a bogey on the 17th saw him slip back into a share of the lead.
The Englishman picked up a further shot on the seventh as he took a brave line to drive the green and get to seven under.
Swede Noren is enjoying an excellent summer having won the Aberdeen Asset Management Scottish Open and reached the final of the Aberdeen Asset Management Paul Lawrie Match Play.
The 2009 champion continued in that vein on Friday with birdies on the 11th, 13th, 14th, first, fifth, seventh and ninth - the highlight being a 20-foot putt on the fifth.
Frenchman Julien Quesne was the first of the afternoon starters to make a move as he progressed to seven under with two birdies in his first five holes.
Paul Peterson remained at six under after four pars with fellow overnight leader Mike Lorenzo-Vera due out in the penultimate group of the day.
Callum Shinkwin closed with a birdie on the last to sign for a 68 and join the group at six under.
England's Ross Fisher was another player to equal the low round of the week, making three closing birdies on his way to a 63 to sit alongside countrymen Tommy Fleetwood, David Howell and Graeme Storm, and French duo Grégory Havret and Alexander Levy.
Australian trio Marcus Fraser, Richard Green and Scott Hend were also at five under in the early stages of their rounds alongside defending champion Danny Willett and Italy's Nino Bertasio.
