BETHLEHEM, Pa. -- Bruce Fleisher wouldn't even let Hubert Green sleep on it.
Hours after Green had the best opening round in the 21-year history of the U.S. Senior Open, Fleisher went one stroke better. His 7-under-par 64 Thursday tied the record for the lowest score in any round of the Senior Open, matching Orville Moody's third round in 1989.
"I drove the ball well, but it's early," Fleisher said. "A lot can happen."
Fleisher held a one-stroke lead over Green and was two strokes in front of Dave Stockton, Isao Aoki and Hale Irwin.
Irwin finished the 18th hole at Saucon Valley Country Club after a 95-minute rain delay. Play was suspended for the day at 8:24 p.m. with nine players still on the course.
"The score I am standing on right now is probably not indicative of how I hit the ball," Irwin said. "It was one of the uglier five under par rounds I've ever had."
Jack Nicklaus shot a 67, which tied his best round in any Senior Open.
"I haven't played a good round of golf in a long time," said Nicklaus, who excited the gallery with his performance. "It was kind of fun. I haven't seen anywhere near a major for a while either."
Jerry Bruner also shot a 67, while four players had 68s.
Defending champion Dave Eichelberger shot a 1-over 72.
Fleisher and Green sit atop the leaderboard for the second time in a month. The two squared off in a playoff last month at The Home Depot Invitational before Fleisher won it with a birdie on the third extra hole.
Fleisher parred the first four holes Thursday before finishing the front nine with four birdies in his last five holes.
He birdied eight holes overall, including three straight beginning at No. 14. He parred nine holes and bogeyed the 18th. His longest putt was a 15-footer at No. 9.
"I started slow, but I kept playing and hit the ball well," he said. "I was able to hit some shots from close. I feel good right now, but a lot can happen in three days."
Fleisher and Stockton benefited from playing in the same threesome as their competitive juices were flowing.
"I tied him at five under (at No. 13), and I think I made him mad," Stockton said. "He went nuts at the end. We fed off each other."
Told what Stockton said, Fleisher joked: "Yeah, I saw him eating peanuts and he didn't offer me any."
They weren't the only ones playing with emotion. After making a putt for a birdie on No. 11, Aoki did a little dance routine, evoking a loud roar from the gallery.
"He said when he gets surprised, he dances like that," said Nobi Kuga, Aoki's interpreter. "He said he's been playing so bad that it's a fluke he played so good."
It's no fluke how well Fleisher has been playing, though.
Fleisher, 51, has been dominant since joining the Senior PGA Tour last year. He's No. 2 on the money list and is seeking his fourth title of the year and 11th since coming aboard.
"I felt very relaxed. I can't even tell you why," Fleisher said. "This sort of golf course, you have to stay in the fairway. It's the only way to be competitive."
Green sensed he would be involved in the competition when he felt the butterflies in his stomach.
He overcame his nerves and shot his best round since a 62 in the third round won him the Audi Senior Classic in March.
"I was talking to my caddie and said that I hadn't been this nervous in a long time on the first fairway," Green said. "It's a great feeling to get those butterflies jumping around in your stomach again."
Before Green's 65, only six golfers had shot a 66 in the opening round of the Senior Open, most recently by Bob Charles in 1996. Charles' round came on a par-72 course, with the other five on par-71s.
Five golfers shot a 66 or better Thursday.
"I don't think this is the most difficult golf course we would play an Open on, but we are not playing the U.S. Open," Nicklaus said. "We are playing the Senior Open. Most of the Senior Open golf courses are set up a little softer than the U.S. Open, probably far more suited for the games of fellows over 50."