Belgium's Thomas Pieters surged to the top of the leaderboard as the second round of the Abu Dhabi HSBC Championship presented by EGA began.
The big-hitting Ryder Cup star, who finished second at Abu Dhabi Golf Club in 2016 and fourth a year earlier, carded five birdies in his first ten holes to race to ten under par.
That put him one ahead of England's Paul Casey, who was seven under for the day with five to play, and Austria's Bernd Wiesberger, who was four under through 12 holes.
Ross Fisher, Sam Brazel, Ryan Fox and Alex Levy were all a shot further back on eight under.
Overnight joint leader Hideto Tanihara slipped back with two bogeys on the front nine while Tommy Fleetwood was among the later starters as the defending champion looked to back up his opening 66.
