Scott Piercy's putter was on fire for the second round in a row, setting up a seven-under 64 to follow his opening 65, and at 13 under he is three strokes clear of the chasing field.
Piercy – who this week changed his coach, swing, caddie, driver and putter – seems to be reaping the benefits of his bold moves, going bogey-free on Friday in a round that included four consecutive birdies to open his round on the back-nine.
He trailed only first-round co-leader Im Sung-jae in strokes gained with the putter on Thursday, and he was again second in that category in his second trip around the course, finishing with 3.96 strokes gained on the greens. Only Danny Willett (5.46 strokes gained) performed better with the flat stick.
In outright second place at 10 under is Argentina's Emiliano Grillo, with a strong 65 that included an eagle. He did not excel in any one area in his first round, but on Friday he was top-10 in both strokes gained putting (3.12 strokes, seventh-best) and in approach shots (2.57, ninth-best).
Grillo is two strokes ahead of England's Callum Taren, who is alone in third place at eight under, and he worked his way there after an even-par opening round.
He shot Friday's round of the day with his eight-under 63, going bogey-free with eight birdies, finishing fifth on the day in strokes gained putting (3.36), second in strokes gained off the tee (2.07) and second in strokes gained tee-to-green (4.92).
There is a five-way tie for fourth at seven under, with American quartet Tony Finau, Robert Streb, Tom Hoge and Doug Ghim, as well as Im after the South Korean followed his six-under opening round with a disappointing 70.
The group tied for ninth are a further two strokes back at five under, which includes Patton Kizzire and Jared Wolfe, while Australia's Cam Davis and England's Willett headlining the group at four under.
Canada's Adam Hadwin finished right on the cut-line at one over, while Davis Riley missed out on the weekend by one stroke, with Beau Hossler at three over and Cameron Tringale at four over.