Lonnie Nielsen is alone in second place at 6-under-par 66. Lee Trevino, Larry Nelson, Dave Eichelberger, Walter Hall, D.A. Weibring and Des Smyth share third place at minus-4.
There was a threat of rain on Friday but nothing accumulated and it turned out to be a great day.
'It's a beautiful day,' said Fleisher, whose 64 was his lowest round of the 2004 season. 'Warming up, I wasn't thrilled with the possibility of rain.'
Fleisher recorded three birdies on the front nine at the Founder's Course at Greystone Golf & Country Club. He ran home a 6-footer for birdie at the par-3 10th and his irons vaulted him to the top of the leaderboard.
He collected back-to-back birdies at 12 and 13, both from inside 8 feet. Fleisher rolled in a 5-footer for birdie at the 16th then made a 20-footer for birdie at the last to go two clear of the field.
But that margin doesn't make Fleisher feel safe.
'I don't think there's a big enough lead for anybody,' said Fleisher, who finished second here last year. 'There is a lot of golf left. I have to continue to be aggressive out there.'
Nielsen, a Champions Tour rookie who earned his card by tying for fourth at last year's Qualifying School, tallied only one birdie through his first eight holes, a 5-footer at the par-5 fifth. He added a 30-foot birdie putt at No. 9 to make the turn at 2 under par.
Nielsen flew up the leaderboard with an amazing stretch at the start of his back nine. He holed a pair of 5-footers for birdie at 10 and 11 and sank a 25-foot birdie putt at the 12th.
At the par-5 13th, Nielsen hit a 4-iron from 230 yards to 45 feet. He drained the eagle putt to get within one of Fleisher's lead. Things came apart quickly for Nielsen as he bogeyed the next two holes but a tap-in birdie at the last got him two off Fleisher's lead.
'When you get it going, you look forward to the next hole,' said Nielsen. 'There are some good birdie holes coming in but I didn't take advantage of them. Although I had a nice run in the middle.'
Bruce Lietzke, Doug Tewell, John Bland and David C. Armstrong are tied for ninth place at 3-under-par 69.
Tom Jenkins, the 2003 winner, opened his title defense with a 1-under-par 71.