Playing on his home course, Na is 14-under-par 128 through two rounds -- bettering the 36-hole tournament record by two shots.
'I started out in the morning knowing it is hard to follow up a 62,' said Na. 'It was going as well as yesterday, but I wasn't hitting it as close. I just tried to stay patient and wait on the birdies to come.'
Thursday, Na played his first competitive round of golf since withdrawing from the PGA TOUR's Shell Houston Open in April. He had been making starts on the PGA TOUR despite breaking his hand in a car door in January.
The 62 he shot in the first round was not only a course record, it also equaled a personal-best at Empire Lakes Golf Course and gave the 23-year-old Rancho Cucamonga resident a two-shot lead.
Now, Na finds himself a comfortable second-round leader at only his second career Nationwide Tour event.
'I just want to keep up what I'm doing,' said Na, who will return to the PGA Tour beginning next week at the Frys.com Open. 'I'm happy with how I've played so far, but we've still got two rounds to go.'
Friday, Na made six birdies and a bogey. His first birdie came on a 15-foot putt at the par-three second, and he added four birdies during a five-hole stretch from the seventh to pull away.
'There are a lot of birdie holes out here,' said Na. 'I know these greens and this course really well. You can always make a bunch of birdies in a row out here.'
Na stumbled to his first bogey of the tournament at the par-4 15th -- just one bogey, but something he expressed considerable disappointment with afterward.
'My dream is to not have a bogey for 72 holes. Tiger has never done that,' said Na, who recovered the stroke with a birdie at the 18th.
Na's closest challengers are Chris Tidland and Dan Buchner, who are tied for second place at 8-under 134. Tidland had a 3-under 68 on Friday, while Buchner fired a 6-under 65 to climb from a tie for 31st place overnight.
Zoran Zorkic had the round of the day, a 7-under 64 that moved him from 69th into a tie for fourth place with six other players. That group stands at 7-under 135.
The cut fell at 1-under 141 with 64 players moving on to the weekend.