Matthew Fitzpatrick recovered from a first-hole bogey to take a two-shot lead at the midway point of the Scandinavian Invitation.
The world number 30 posted a six-under-par 64 in round one but made a disappointing start to his second round as he immediately dropped a shot on a par four.
However, he made up that stroke at the fourth and, after making the turn in a level-par 36, rediscovered his Thursday form with a blistering back-nine display.
He birdied the par-three 10th before further gains at 13 and 15 after putts from 30 and 35 feet. Fitzpatrick sent his approach at 16 to three feet for another gain before finishing with a birdie on the last.
Fitzpatrick's 36-hole total of 129 marks the lowest of his career, but he will be looking over his shoulder at the home hope who heads the chasing pack, as Henrik Stenson delighted the Gothenburg crowd with a superb 62.
Stenson also bogeyed the first but responded with back-to-back gains and then produced a run of six successive birdies starting at the eighth.
The 2016 Open champion replicated Fitzpatrick in birdieing the 18th to put himself firmly within striking distance. Wu Ashun is level with him on nine under after a 64.
Joakim Lagergren and Jason Scrivener are three shots off the pace. Wade Ormsby, who led through 18 holes after his 62, is in a group of four players on seven under after a 71.
Alex Noren made the cut in thrilling fashion, carding four straight birdies to close the round in 67 and take him to one under for the tournament.