Duffy Waldorf fired a 4-under 68 on Friday and grabbed a 1-stroke lead through two rounds the Regions Tradition.
Waldorf, who is seeking his first Champions Tour victory, is 9-under 135 through 36 holes at the season's second major, which was delayed over three hours on Friday due to rain.
"Pretty much every tournament I come to is kind of a first time," said Waldorf, who is making his 14th start on the circuit. "It's kind of an adventure ... It's fun being a rookie out here."
First-round leader Jeff Sluman shot 71 at Shoal Creek Club and dropped into second place at 8-under.
"I played pretty good today, made a few mistakes, didn't make as many putts obviously. I was very happy," said Sluman.
Two-time Champions Tour major winner Fred Couples (71), Mark Calcavecchia (69), Michael Allen (69) and Rod Spittle (66) are tied for third at 7-under, while David Frost (70), Mike Goodes (68), Loren Roberts (69), Peter Senior (71), Bart Bryant (69) and John Cook (68) share seventh at minus-6.
"I'm tired now, but I felt pretty good out there," said Couples. "I just couldn't hit the ball close enough, and when I did, I had some pretty good putts and I felt like I putted well, but nothing went in."
Two-time defending champion Tom Lehman, who is trying to join Hale Irwin as the only player to win the same major on the Champions Tour in three consecutive years, carded a 71 on Friday. He is tied for 19th at 4-under.
Waldorf opened with a par, then birdied the second before play was halted.
When the four-time PGA Tour winner returned to the course, he carded a pair of pars, then picked up back-to-back birdies from the fifth to jump ahead of Sluman, who had just stumbled to a bogey at the 12th.
Sluman managed to hit the clubhouse with the lead, however, courtesy of a birdie at the 17th, paired with Waldorf's bogey at the ninth.
Waldorf, though, gained momentum around the turn. grabbing a share of the lead at 8-under with a birdie at the 10th, then moving a shot ahead thanks to a gain at the 12th.
Another birdie at the 15th pushed Waldorf's advantage to two, but he tripped to a bogey at the next hole, then parred out to end at 9-under.
"It really poured there for a while," he said. "We were looking outside and we were going, my gosh, it's going to take hours for the course to drain, but we got back out pretty quick.
"It was pretty dicey there early, it was raining and not looking great and super wet and a little sloggy. But for me, I didn't get off to a good start. I was on the third hole and didn't hit a very good second shot, but played really well after that."
NOTES: Waldorf finished third last week at the Principal Charity Classic, his best performance on the 2013 Champions Tour. He made his first appearance in a senior major championship two weeks ago at the Senior PGA Championship and tied for sixth ... Lehman, Jack Nicklaus, Gil Morgan and Fred Funk are the only players to win this event more than once. Irwin won the PGA Seniors Championship from 1996-1998 ... Sluman is seeking his first major title on the Champions Tour and his sixth victory overall.