Making his competitive return at his home course, Na fired a 9-under 62 on Thursday to take the lead after one round of the Mark Christopher Charity Classic.
Na, 23, equaled the course record -- and his own personal best -- at Empire Lakes Golf Course in his first tournament since withdrawing from the PGA TOUR's Shell Houston Open in April.
Ignoring his doctor's advice, Na had made nine PGA starts after breaking his hand in a car door in January. All that ended in Houston more than five months ago.
'It was stupid to try and play after that (hand injury). I was taking so many painkillers,' admitted Na. 'I finally got to the point where I knew if I kept playing my future was going to be bad.
'I'm excited to be back. I'll play next week in Vegas and then in Tampa and then I'll have 20 tournaments next year to keep my (PGA TOUR) card.'
Once the youngest player on the PGA TOUR (he was 20 for most of the 2004 season), Na made his only other Nationwide Tour start at this event in 2001, missing the cut when he was just 18.
His bogey-free round on Thursday equaled the course record set by Steve Haskins in 2001, when the course played as a par-72, and equaled by Jess Daley in 2003.
'I knew the course record was a 62 and my best round out here is a 62,' said Na, a Rancho Cucamonga resident. 'When I birdied the seventh hole -- my 16th of the day -- I knew I needed one more to break the record.'
But Na finished with two straight pars to tie the record and take the first- round lead.
'[A]lthough it was a 62, it was tough,' Na said of his afternoon round. 'I would say it probably played two strokes tougher than it played this morning.'
Jason Allred, Chez Reavie and Bob Heinz each shot 7-under 64 to share second place, two shots behind Na. David Sutherland, Tom Scherrer and Jimmy Walker were one stroke further back at 65.