American Cameron Young shot a 6-under 64 to go three strokes ahead at the halfway point of the Dubai Desert Classic, with defending champion Rory McIlroy well off the pace.
Young made nine birdies and a solitary bogey as he added to his opening 67 to reach 13 under par overall.
The Englishman Andy Sullivan and the Polish Adrian Meronk are his closest challengers at 10 under.
McIlroy, three-time winner of the event, is 10 shots behind Young.
The Northern Irishman recorded five birdies in his second round, but had to regret his lost shots on the eighth, ninth and eleventh holes.
Meanwhile, world number 25 Young, who is aiming for a maiden victory on both the PGA Tour and DP World Tour, said: “I made some fantastic putts. I made a few long putts yesterday , then I made a few more today that had no right to enter.
“I made a bunch of good putts, but just one of those days where you kind of have a couple 30-footers and you look up and they’re going right down the middle, which doesn’t happen that often to get a one bunch of them in one round.
“I’m doing a really good job of staying away. I realized it was going well early, but the back nine, at the same time, I feel like you should do that to some extent, especially in the morning, with not much wind.”
Meronk, who won three times on the DP World Tour last year and was voted player of the year by his peers, recorded three birdies on the front and three on the back nine as he carded a six -under 66, while Sullivan returned a second in a row. 67.
Dubai Invitational winner Tommy Fleetwood celebrated his 33rd birthday with a 70 to finish five under overall, three shots ahead of compatriot Tyrell Hatton and European Ryder Cup captain Luke Donald.