Sung Kang tied the Golf Club of Houston course record on Friday with a second-round nine-under 63 that also broke the previous 36-hole scoring mark at the Houston Open.
Kang was flawless in round two, putting up seven birdies with an eagle on the par-five eighth hole, which was his 17th.
Now at 16 under, Kang has a six-shot lead heading into the weekend.
"I putted pretty good yesterday, putted really good today," Kang said following Friday's round, via golfchannel.com. "Plus I teed off the first, and the greens are just pure, nobody really had them. The putter just kept making the putts."
"I always hit it long and straight enough, but I always have trouble with iron play and also putting," Kang added. "My putting was not bad last year. We've been working so hard on my iron play. It keeps getting better. I still was hitting irons so much better, but I didn't putt well through last week."
Sung Kang's explanation for his bogey-free 63,-- PGA TOUR (@PGATOUR) March 31, 2017
"The putter just kept making the putts." pic.twitter.com/LB595LoH8N
Hudson Swafford and Russell Henley climbed into a tie for second at 10 under. Both players have shot consecutive five-under 67s.
Rickie Fowler limped home after reaching 12 under at one point Friday.
Fowler finished at nine under after shooting a one-under 71 with a double-bogey and a bogey on two of his last four holes.
Struggling were Jordan Spieth, Adam Scott and Henrik Stenson, the high-profile trio all missing the cut.
Aaron Baddeley and Zac Blair head into the weekend tied for fifth at eight under. Baddeley has yet to record a bogey through 36 holes.