Keegan Bradley shot a second round 66 to kick clear of the field in the PGA Tour's CIMB Classic in Malaysia.
The American's six-under round which featured seven birdies and a bogey lifted him four clear of first-round leader Ryan Moore, who could only add a par round of 72 to his superb opening 63.
Bradley made steady progress early on after teeing off at the 10th, with birdies at 10 and 16 separated by a dropped shot on the 13th.
But five birdies in six holes on his second nine saw the 27-year-old come home in 31 and set the impressive halfway total of 13-under 131.
So far, 2011 US PGA champion Bradley has hit 24 fairways out of 28 and he reckons the par 72 Kuala Lumpur Golf & CC layout suits him down to the ground.
"It's challenging, it's very tight and you've got to drive the ball straight," said Bradley. "It's a really good course for me."
Moore started brightly with birdies at 10 and 12 to move to 11-under but lost momentum with three bogeys after that and needed a four at the par five last to avoid shooting over par.
"I seemed to be in that 15-to 20-foot range today and just wasn't able to convert them," said Moore. "But I'm in a great spot, obviously, enjoying the course and playing well."
Thailand's Kiradech Aphibarnrat, who won the European Tour event held at this course back in March, again showed his liking for this layout by carding a 69 to move up to tied third alongside another American, Chris Stroud (69). That pair are five behind Bradley.
Sergio Garcia suffered a sticky start with bogeys at the first two holes but recovered to shoot a one-under 71 to keep in the hunt at seven-under - six behind.
The Spaniard shares fifth place with Marc Leishman, who shot the round of the day. The Aussie played the tougher back nine in one-under but shot a 30 on the second after an eagle at the fifth, five birdies, two pars and a bogey.
Pre-tournament favourite Phil Mickelson, who admitted he drove the ball terribly in round one, shot a two-under 70. That left him in tied 25th place, a full 10 shots behind Presidents Cup playing partner Bradley.