Danny Lee fired a 7-under 65 on Saturday to grab a 2-stroke lead after three rounds of the WNB Golf Classic at Midland Country Club.
Lee finished 54 holes at 16-under-par 200.
He is in position to become the first player in tour history to successfully defend a title. Lee's win at this event last year was his only tour title.
Second-round leader Morgan Hoffmann managed a 2-under 70 to slide into a tie for second at minus-14. He was joined there by Cameron Percy (66).
Jamie Lovemark carded a 3-under 69 and is alone in fourth at 12-under 204.
Aaron Goldberg shot a 66 to move into a tie for fifth at minus-11. He stands alongside Luke Guthrie and Justin Hicks, who both posted 67s in round three.
Lee, who played most of the year on the PGA Tour, doesn't have a top-10 finish all season on either tour. He has gone 16-under par over the last two rounds after an opening round, even-par 72.
"I lost three balls out there, hit a couple in the bushes, had one unplayable lie and hit it in the water on 17 and made double. I did good just to finish at even par," Lee said of his first round.
The 2008 U.S. Amateur champion birdied the first, but gave that shot right back as he bogeyed the par-5 second. He caught fire starting with a birdie on the fourth.
Lee followed with birdies at five, six and seven to make it four in a row. That spurt gave him the lead at 13-under. He parred the next four holes before converting a birdie chance on the par-5 12th.
The 22-year-old came back with a birdie on the 14th. After three pars in a row, Lee birdied the last to stretch his lead to two.
"I hit it better. I putted it better. Somehow, every time I hit it on the green I can read the greens really nicely. I don't know if it's the green color, or it's Midland, or I'm just having a good time," stated Lee.
Hoffmann had two birdies and two bogeys on the front nine. Around the turn, he converted back-to-back birdie efforts from the 10th to get to 14-under. Hoffmann parred the final seven holes to end there.
"That was the craziest day I've had in a long time. I was everywhere," Hoffmann said. "I don't even remember the last fairway I hit. I'm still in it. This was just a day you put behind you."
Percy birdied the first and second. He parred the final seven holes of the opening nine, then ran off four birdies in the first five holes around the turn. Percy parred the last four to end at 14-under.
NOTES: Lee's best finish on either tour was at last week's Web.com event in Boise, where he tied for 13th. His best PGA Tour finish of the year was a tie for 19th at the Byron Nelson Championship...Ten players have won the same event two times on the Web.com Tour, but never in back-to-back years...Adam Long had a hole-in-one on the par-3 16th.