Fleisher shot a 1-under-par 69 to take a one-shot lead in the 22nd U.S. Senior Open.
Frank Conner and Gil Morgan are tied for second place after a pair of even-par 70s. Jack Nicklaus heads a group of players at 1-over. Nicklaus, Isao Aoki, Walter Hall and Dana Quigley all opened in 71.
Fleisher led after each of the first three rounds at Saucon Valley in Bethlehem, Penn., a year ago. However, a two-shot lead turned into a three-shot defeat to Hale Irwin, who closed in 65 to win his second Senior Open in three years.
God, I hope I do get in position like I did last year, Fleisher said. I just dont want to get Hale Irwin mad. Thats all.
Fleisher has won 13 times in less than three years on the 50-and-over circuit, though none of those have come in a major championship.
Thursday, he was the only player to break par on a difficult layout in Peabody, Mass.
The pin placements I thought were very good and very fair ' very difficult, he said.
Added Nicklaus: I think we probably played about a dozen pin placements that I didnt think we would see. Which was fine, because they didnt take the greens and make them lightning fast so we couldnt play them.
Perhaps more than his score, Fleisher enjoyed the company he kept on Thursday.
Fleisher played alongside Nicklaus and Raymond Floyd, who shot 72.
Who would have thought Bruce Fleisher would be the best player in this threesome, quipped television announcer Johnny Miller.
The trio started on the back nine. It marked the first time in tournament history the USGA used split tees.
Fleisher played steadily, making the turn in even-par 35. However, Nicklaus struggled, carding a 3-over-par 38.
Upon making the turn, the two-time Senior Open champion found his groove. He birdied the par-4 1st and the par-5 6th for a bogey-free 33 on his inward half.
After shooting 38 for the front nine, you bet Im pleased to come back to shoot 71, said Nicklaus, who hasnt won since the 1996 Tradition.
Fleisher also birdied the 1st and then posted eight straight pars to close his round.
One player who had problems coming home was the defending champion.
Irwin was 1-under-par through 13 holes, but finished with two bogeys and a double bogey over his final five holes.
Im very frustrated with my game right at the moment. In fact, Im very irritated with things right now, said Irwin, who opened in 67 in the U.S. Open two weeks ago.
Ive been working very hard. Im trying to get my game back in shape. It seems like the more I work, the less I get out of it.
Tom Kite, who shot a final-round 64 in the U.S. Open, is also at 3-over-par following a 73.
Full-field scores from the U.S. Senior Open