Kang drained a 30-foot putt for eagle on his penultimate hole, the par-five eighth, to go along with seven birdies for a nine-under-par 63 that tied the course record at the Golf Club of Houston in Humble, Texas.
"I putted pretty good yesterday, putted really good today," said Kang , who needed 25 putts over his round. "Plus I teed off first and the greens are just pure, nobody really had them. The putter just kept making the putts."
Americans Hudson Swafford and Russell Henley were in a share of second place after both shotting 67s while first-round leader Rickie Fowler (71) was a further stroke back in fourth place.
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Kang, who is ranked 202nd in the world and has missed the cut in seven of his last 12 starts, started his day one shot off the pace and will now try to hang on as he heads into the weekend with hopes of securing his first Masters invite.
"It's not in my head. I'll go play," said Kang. “Whatever happens, happens."
(This version of the story corrects Kang's margin of lead to six shots instead of four in first para of story originally moved on March 31)
(Reporting by Frank Pingue in Toronto, editing by Nick Mulvenney)
