After two top 10 finishes in the last two tournaments, Quinney shot an 8-under 63 on Friday to open a three-shot lead halfway through the FBR Open.
'Other than probably a couple of majors, I think this is where I'd want to win,' he said.
Quinney, a PGA TOUR rookie, was at 13-under 129 through 36 holes after a dominating second round under bright sunshine at the TPC Scottsdale course.
and Bart Bryant were three shots back at 10-under 132 after 66s.
Bubba Watson, John Rollins, Robert Garrigus and Charles Howell III were four back at 9 under. Play was suspended because of darkness Friday with 18 players on the course. Howell was one of them, finishing his final two holes with pars Saturday morning.
Quinney acknowledges he was uncertain about his career when he turned professional in 2001.
'I probably didn't trust myself enough,' he said.
It took five years of struggle and initially not much success before he qualified for the PGA TOUR by finishing sixth on last year's Nationwide money list.
He said he is surprised by how well he's done this year -- a tie for fourth at the Bob Hope Classic and a tie for seventh at the Buick Invitational.
'But you shouldn't be in a way,' Quinney said. 'This is why you play the game, to contend and to compete. You just don't go out there to finish 30th place and kind of squeak by. This is where I want to be. I want to be in contention and in front of the lights.'
Mayfair, who also played golf at Arizona State, hasn't won on the tour since 1998 and is coming off a difficult year that included a divorce, surgery for testicular cancer and his mother's stroke.
But his game has been terrific this week on a course that's just a few hundred yards from his home.
He chipped in from 85 yards for an eagle on the 552-yard, par-5 15th hole to reach 11 under before his only bogey of the day on the 18th.
'I hope an old guy wins once in awhile like myself,' the 40-year-old Mayfair said, 'but it's good to see these young guys come off the Nationwide Tour and start playing well immediately out here, because that's what that tour is for.'
Bryant, finishing just before darkness fell, made a birdie on his final hole, the 464-yard, par-4 ninth.
Quinney had nine birdies and one bogey on the 7,216-yard layout, where the start of play was delayed 40 minutes Friday by frost. But the sun quickly made conditions ideal.
'It was one of those days where you get in the zone and you feel like nothing can go wrong,' Quinney said.
Playing with Tiger Woods at the Buick Invitational last Saturday was an added boost.
'Just to be thrown in the fire, playing against the No. 1 player in the world,' Quinney said. 'It seemed like he was heads above everybody else. To be right with him playing 18 holes -- I think I bogeyed the last hole and lost by one to him that day -- but that just kind of proved to me that I can play at this level, and on the weekend. It just gave me a lot of confidence.'
Two-time FBR champion Phil Mickelson is finished for the week. He shot a 69 on Friday for a 1-under 141 and missed the cut by one stroke.
Mickelson tied for 45th at the Hope Classic and 51st at the Buick Invitational. He has not finished better than tied for 16th since his 18th-hole collapse at last year's U.S. Open.
'Well, it's not the start I wanted to the year,' he said. 'I'm going to work on it this weekend and see if I can get the putter working.'
For the sixth consecutive year, Woods is skipping the FBR event, opting to play halfway around the world at the Dubai Desert Classic. Next year's FBR Open will be held the same week as the Super Bowl in nearby Glendale. ... FBR officials met with Woods in San Diego last week to try to persuade him to enter next year's event.