John Harris is alone in second place at 6-under-par 66 while Tom Kite, Rocky Thompson, Mike McCullough and Walter Hall are tied at minus-5 at Nashawtuc Country Club.
Purtzer parred his first two holes on Friday, but went on a birdie tear shortly after that. He drained a 12-footer for birdie at the third, then missed the green short with his drive at the 298-yard fourth. Purtzer chipped to a foot and tapped in for birdie, then made it three in a row with a two-putt from 40 feet at the par-5 fifth.
He reached 4 under par with a 15-foot birdie putt at the seventh, but trouble loomed. Purtzer three-putted from 18 feet for a bogey at the eighth and closed his front nine with back-to-back bogeys when he went over the green at the par-5 ninth.
Purtzer reclaimed one lost stroke at No. 10, also a par-5. He knocked a 4-wood to 40 feet with his second shot and two-putted for the birdie.
Purtzer went on another birdie run, starting at the 14th. He holed a 15-footer at the 14th, a 12-footer at No. 15 and closed the string of birdies with another 15-foot birdie putt at the 16th.
He got to the putting surface in two with a 4-iron at the closing hole. Purtzer took two putts from 50 feet to get down for the closing birdie and his second opening-round 65 at this event.
'I enjoy this course,' said Purtzer, who tied for fourth place last year. 'This is old-style and a fun course to play. If you drive it good, you can make some birdies.'
Harris tallied five birdies through his first 13 holes, but cooled off after that. He parred four consecutive holes, but birdied No. 18 to get within one of the lead.
Kite, who made the cut last week at the U.S. Open, was 2 under on his round, but got going later on the second nine. He sank an 18-foot birdie putt at the 13th, then added his fourth birdie of the round at the 15th. Kite closed with a 15-foot birdie putt at the last for one of three bogey-free rounds on Friday.
'It was a good day,' said Kite. 'I hit the ball very well today. The year hasn't been very good. Right now, I've changed some things on my putting and I'm putting better.'
Thompson mixed seven birdies and two bogeys on Friday, while Hall recorded six birdies against one bogey.
McCullough was 4 under on his front nine, including a 5-foot eagle putt at the fifth. He dropped a shot at the par-3 13th, but kicked in a short birdie putt at 15 and rolled home a 40-footer for birdie at 16 to get within two of the lead.
Craig Stadler, Eamonn Darcy, Jay Sigel, John Jacobs, Dana Quigley, Lanny Wadkins, Fred Gibson, Jerry Pate and Bill Rogers are tied for seventh place at 4-under-par 68.
Allen Doyle, who won the rain-shortened Bayer Celebrity Pro-Am two weeks ago and won this event in 2003, opened his title defense with a 1-under-par 71 and is part of a group tied for 33rd place.