Ryan Hietala, Greg Kraft, Franklin Langham and Gavin Coles share second place after each posted rounds of 6-under-par 66. Tom Byrum, winner of the 1989 Kemper Open, is one shot further back at minus-5. He was joined there by Matt Hendrix and Michael Connell.
Allen started on the front nine at Panther Lake and collected his first birdie at the par-5 second. He later birdied the sixth and ninth to turn in minus-3.
The 46-year-old stumbled to his only birdie on the par-5 10th. Allen then birdied the next two holes to get to minus-4. He converted back-to-back birdies from the 14th and again from the 17th to jump to 8 under.
Hietala birdied two of the first three holes at Crooked Cat. After a bogey at the fourth, he birdied each of his next two holes to get to 4 under. The 32-year-old birdied No. 9, but bogeyed the next. Hietala birdied three of four holes from the 14th to finish at minus-6.
Langham played the back nine at Panther Lake first. He sank consecutive birdies from the 13th and 17th to turn at minus-4. After four straight pars, the 37-year-old sank birdies on five and six to tie for second place.
Kraft played the back nine of the Crooked Cat course first and birdied two of his opening nine holes. The 41-year-old collected three birdies, an eagle and a bogey around the turn to share second.
Coles birdied the first at Crooked Cat, then posted five birdies in a seven-hole stretch from the eighth to get to 6 under. He parred his final four holes to end there.
Bill Haas, son of PGA and Champions Tour player Jay Haas, opened with a 4-under-par 68. He shares ninth place with Johnson Wagner, Robert Garrigus, Bob Heintz, Tom Johnson, Jeffrey Overton and Jay Don Blake.
Among those a minus-3 is 2003 Q-school medalist Mathias Gronberg. Notah Begay III, who played last season on a major medical exemption due to back problems the last few years, opened with a 1-under-par 71 and is tied for 50th.
Former Masters champion Larry Mize carded an even-par 72 Wednesday, as did PGA Tour veteran Deane Pappas.