Steve Lowery, the runner-up in last year's event, made five birdies and one double-bogey in a 3-under 68. He finished alone in fourth at 11-under 202, while Kevin Sutherland (69) and second-round leader Craig Barlow shared fifth place at minus 10.
Northern Ireland's Darren Clarke birdied five of his first six holes on the way to a 66 that matched Sauers and Brandt Jobe for low round of the day at Northview Golf & Country Club. Clarke jumped from 38th place into a tie for seventh at 8-under with Blaine McCallister (70) and David Gossett (72).
Vijay Singh, the highest ranked player in the field at No. 9 in the world, rounded out the top-10 as part of a 10-man logjam that included Jobe, defending champion Joel Edwards and 2000 Air Canada winner Rory Sabbatini. The group finished six shots off the pace at 7-under-par.
Sauers, who started Saturday's play two strokes off the lead, began his climb to the top of the leaderboard with a 25-foot birdie putt at the third hole followed by three straight birdies from the fifth to the seventh.
In between clubs with his approach to the par-4 10th, Sauers chose a 9-iron but came up short of the green. He chipped up then missed a 10-foot par putt for his first dropped shot since his initial hole of the tournament, ending a streak of 44 bogey-free holes.
Sauers immediately struck back at the 157-yard, par-3 11th hole, where he knocked a 9-iron to 25 feet and rolled in the birdie to return to 12-under. He moved to 13-under at the par-5 12th after he blasted his third shot out of a bunker and sank an eight-footer for birdie.
Sauers, who turned 40 last week, was a regular in the top-50 on the PGA Tour money list from 1986, the year he won his first title at the Bank of Boston Classic, until 1992. He also captured the 1989 Hawaiian Open and the 1990 Deposit Guaranty Golf Classic, which was an unofficial event.
His last full year on the PGA Tour was 1996. Sauers made 16 of 25 cuts that season but raked in only $123,904 to finish 148th in earnings.
'I haven't played in that many regular tour events this year or in the past lately because I lost my card and I kind of got tired with the game,' said the Georgia native, who has competed on the Buy.Com Tour since 1997 and won its 1998 South Carolina Classic.
'I wasn't happy out here, the way I was hitting it. I was hitting it in the rough, and you can't play golf out of the rough. It really got frustrating. Now I have some new irons, a new driver and I am hitting the fairways. Things are looking back up again.'
Sauers, who has finished in the top-10 in his last two starts on the Buy.Com Tour, made three previous appearances on the 2002 PGA Tour -- all in July. He tied for 48th in both the Greater Milwaukee Open and B.C. Open, then tied for 40th at the John Deere Classic.
Should he hold on and win on Sunday, Sauers would collect $630,000, nearly $200,000 more than he made in his best full season. He would also earn a two-year exemption on the PGA Tour.
'I haven't had my tour card for the last six or seven years and it's nice to come out here and have that opportunity,' Sauers said. 'I don't really want to go back to (PGA Tour Qualifying) school, so let's hope that I can put it all together tomorrow and not have to worry about that.'
Allenby, who fired a course-record 63 en route to a second-place finish at last week's WGC-NEC Invitational near Seattle, continued to go low this week with a career-best 62 in Friday's second round. Despite two early bogeys on Saturday, Allenby kept in touch with the leaders with four birdies on the back nine.
'The front nine wasn't the best of starts,' admitted Allenby, 31, who dropped shots at the second and fifth holes but managed a birdie at the third. 'I mentally turned it around on the back nine and they are the thoughts I need to take into tomorrow.'
Allenby chipped and putted from short range for birdie at the par-5 12th, then picked up another shot with a 12-footer for birdie at the 14th. He closed with birdies on the last two holes, first knocking a pitching wedge to six feet at the 17th then rolling in a 25-foot putt at the 18th.
'I was a good way to finish,' he said.
Lonard, a three-time winner on the Australasian Tour who is in the midst of a successful rookie campaign on the PGA Tour, produced a pair of eagles Saturday in a round that also included four bogeys and three birdies.
'I sort of bungled through,' Lonard said. 'I was lucky enough to make a couple eagles on the par-5s.'
The 35-year-old Aussie drained a 90-foot putt at the 584-yard seventh. He later secured a less improbable eagle when he struck a 3-wood shot to six feet at the 548-yard 12th. He is a combined 10-under on the par-5s this week.
Lonard added a 20-foot birdie putt at the 13th and a three-foot birdie at the 15th to tie Sauers for the lead at 13-under-par. He three-putted from 50 feet for bogey at the 17th, however, missing his par putt from four feet.
Lonard has yet to miss a cut in 20 starts on the 2002 PGA Tour.
'I think I'm getting closer,' said Lonard, who has three top-10 finishes and 10 others in the top-25 this season. 'The more I hang around and knock on the door, one day the door will open, and I'll swing past and get one.'
Full-field scores from the Air Canada Championship