Denmark's Lucas Bjerregaard set an imposing clubhouse target as overnight leader Sergio Garcia stumbled in the second round of the BMW Masters in Shanghai.
World number 11 Garcia held a one-shot lead after an opening 64 and initially remained out in front on Friday thanks to birdies on the third, sixth and seventh at Lake Malaren, which was again playing every inch of its 7,594 yards.
However, the 35-year-old Spaniard then three-putted the 12th to drop his first shot of the day and ran up a double-bogey seven on the 13th, pulling his second shot into the water and taking three to get down from just short of the green.
That meant Garcia was suddenly four behind the in-form Bjerregaard, who had carded a second consecutive 66 to finish 12 under par - three clear of Thailand's Thongchai Jaidee, who was also safely in the clubhouse after a 68.
Paul McGinley shot another round of 71 to go to two under, while Shane Lowry (+1) slipped down the field with a three-over-par 75.
"It was a great round and obviously finished off with some good birdies coming in," said Bjerregaard, who covered the back nine in 35 after starting from the 10th and birdied five of his last eight holes to come home in 31.
"Nothing much really happened on the first nine, just played really solid. But I thought it was a good bit tougher than (Thursday) with the wind up. Some of the holes were playing really long."
Bjerregaard, who was edged out by former US Open champion Justin Rose in the Hong Kong Open three weeks ago, added: "It was nice in Hong Kong to prove to myself and to everyone else that I can still compete up there. Hopefully I can do that again this week and just come up one place better than last time."
England's Ross Fisher, who lost out in a three-man play-off here 12 months ago, was alongside Jaidee on nine under with four holes to play, with compatriot Ian Poulter eight under after a second successive 68.
American Peter Uihlein, who was playing alongside Bjerregaard, was six under after a 66 which featured seven birdies in succession from the 15th, the former rookie of the year narrowly missing from 15 feet on the fourth to make it eight in a row and equal the European Tour record.