Coles snapped the previous course record at the Crestview Country Club's North Course by one shot, collecting 10 birdies in a flawless second round that put him at 12-under-par 130 for the tournament.
Matt Kuchar shot a 7-under 64 to join Coles in the lead, moving up from 11th place after the first round. Coles made the jump all the way from a tie for 58th.
'Every now and then it clicks and you have a nice day,' said Coles, who holds at least a share of the 36-hole lead for the first time. 'You just have to go out there and play tee-to-green and make a few putts.'
Coles' 61 bettered Deane Pappas' opening-round 62 in the Wichita Open last year. It was also a career-low score for the Australian -- at least on the Nationwide Tour, although he wasn't so sure of that when he finished his round.
'I would imagine so,' he said. 'I'd have to go and take a look.'
Coles' previous low score was a 63 during the opening round of the 2004 Price Cutter Charity Championship. He has now carded nine career rounds of 65 or better on the Nationwide Tour, including two at this event.
He shot a 65 at this course in the first round of the 2005 Wichita Open and went on to tie for 14th place.
'You always come back to a place you like and you feel like you can win at,' said Coles, who won the last of his two Nationwide Tour titles at the 2004 New Zealand PGA Championship.
Beginning his second round on the back nine, Coles birdied the 11th, 14th and 15th holes -- all on putts inside eight feet.
He rolled in a 30-footer for birdie at the 17th, made an 8-footer at the 18th and then collected his third straight birdie when he chipped in at the par-4 first.
Coles also carded three consecutive birdies beginning at the third -- again, all on putts inside 8 feet. He wrapped up his bogey-free round with a 15-foot birdie putt at the ninth.
When it was all over, the 37-year-old Coles had mostly his stellar iron play to thank for such a low score.
'I hit it inside 10 feet a lot today,' he said. 'It was a lot of fun.'
The first round, delayed by two weather stoppages, was suspended by darkness Thursday night with a large group of players remaining on the course. One of them was Kuchar, who played 19 holes Friday.
'I came out this morning and played one hole. I parred it, which was disappointing,' he said.
After that, it was smooth sailing.
Kuchar began his round on the back nine, too, and collected six of his seven birdies there.
Mirroring the iron play of Coles, five of Kuchar's birdies came on putts inside 8 feet. His longest was a 20-footer for his first birdie at the par-4 11th.
On the front nine, it was a different story: eight pars and a birdie at the par-four third.
'The front side is definitely tougher than the back side,' admitted Kuchar, who is enjoying his first second-round lead.
Hunter Haas shot a 64 and is alone in third place at 11-under-par 131. Josh Broadaway (67), Scott Parel (67) and Barry Cheesman (66) are tied for fourth at minus-10.
First-round leader Tim Wilkinson stumbled to a 2-over 73 and fell into a tie for 43rd place at 5-under-par -- two shots from missing the cut.