Christiaan Bezuidenhout carded a second-round 65 to surge into a four-shot clubhouse lead on day two of the Made in Denmark.
The South African followed up his opening 66 at Silkeborg Ry Golf Club with a seven under par effort to equal Bradley Dredge's tournament record of 13 under after 36 holes.
England's Matthew Baldwin was the nearest challenger after a 69 that left him a shot ahead of countrymen Matt Wallace, Sam Horsfield and Jonathan Thomson.
Wallace carded a second consecutive round of 68, Horsfield was three under after five holes of his second round and overnight leader Thomson was yet to start after his brilliant 64 on Thursday morning.
In the race to take the final automatic spot in the Ryder Cup Team, Eddie Pepperell and Matthew Fitzpatrick were facing an uphill battle to claim the victory they needed to potentially overhaul local hero Thorbjørn Olesen.
The biggest 36-hole deficit made up by a winner this season is nine shots by Alex Noren at the HNA Open de France, and Fitzpatrick will at least have to match that after a second-round 68 moved him to four under.
Pepperell was one shot better off after a 69, with Olesen heading out in the afternoon after an opening 73.
If Fitzpatrick were to win, a tie for seventh with one other or better would see Olesen keep the final place, while a top 12 from the Dane would keep a victorious Pepperell at bay.
Bezuidenhout moved into a share of the lead with birdies on the fourth and sixth before dropping a first shot of the week on the eighth but he bounced back in style, birdieing the ninth and tenth to take top spot on his own.
Further gains on the 11th and 12th made it four in a row and Bezuidenhout led by three but the chasing pack were jostling behind him.
Countryman Erik van Rooyen added to birdies on the third and eighth with gains on the 11th and 12th to cut the lead to two but Bezuidenhout edged back clear with a gain on the 14th.
Baldwin had made a bogey on the second but gains on the ninth, 11th, 12th and 14th had him within three before Bezuidenhout holed a 15-footer on the 16th to lead by four.
A Baldwin birdie on the 16th cut the gap again and Wallace - already a two-time winner on the European Tour this year - was making his move after a shaky start.
He bogeyed the 12th and 13th but eagled the par five 14th and then birdied the 16th to turn in 35.
A second eagle of the day came on the third when he spun his second back into the hole and after taking advantage of the fifth and holing a chip on the sixth, he was nine under.
A stunning tee-shot into the par three seventh meant he had picked up five shots in as many holes and he was three behind Bezuidenhout who finished with two pars to card the best 36-hole score of his European Tour career by six shots.
Baldwin bogeyed the last and with Wallace dropping a shot on the par five eighth after chipping into a bunker, the lead was back to four.
Wallace made another bogey on the ninth, while Van Rooyen dropped shots on the 16th and 18th to drop six shots off the lead alongside countryman Richard Sterne, Thai Phachara Khongwatmai, Spaniard Adrian Otaegui, English pair Robert Rock and Callum Shinkwin, and Paraguayan Fabrizio Zanotti.
