Gavin Coles, Brenden Pappas and Cameron Beckman are knotted in second place at 4-under-par 67 at StoneWater Golf Club.
Quinney, the 2000 U.S. Amateur Champion, started on the back nine Thursday and parred his first hole. He traded a pair of birdies and a pair of bogeys over his next four holes, then birdied 18 to make the turn at minus-1.
Quinney birdied the par-3 third and followed that with an eagle at the par-5 fourth before recording another birdie at the par-4 eighth. He parred the ninth to grab his shared of the lead.
He is sixth on the money list and recently took a two-week break away from the game without touching a club, something he feels helped him on his back nine Thursday.
'I'm one of those guys who need a break,' admitted Quinney. 'I didn't feel like I was sharp. Mentally I was asleep. It was hard to find the groove, but I settled down and had a really good back nine.'
Zorkic played in the afternoon on Thursday and also played the back nine first. Like his fellow co-leader, Zorkic mixed three birdies and two bogeys to go out in 1 under par.
On the second nine, Zorkic tallied birdies at two, four, seven and eight to join Quinney in first place, an unlikely spot for a player who only hit half of his fairways on Thursday.
'Luckily I hit a lot of close iron shots,' said Zorkic. 'I also putted good which was nice. The greens are very tough and extremely fast. Compared to Wednesday, they've got to be rolling five feet faster.'
Defending champion Andrew Johnson started strong in his defense. He carded a 3-under 68 in Thursday's first round and is tied for sixth place with Roberto Coceres.
Paul Claxton, Deane Pappas, Jarrod Lyle, Chris Anderson, Josh Broadway and Akio Sadakata are knotted in eighth place after opening with rounds of 2-under-par 69.