Craig Stadler fired a 7-under 65 on Saturday to jump into the top spot of the inaugural Encompass Championship.
Stadler finished 36 holes at North Shore Country Club at 12-under-par 132.
"I was good with the short irons, really good with the putter," said Stadler. "I hit a lot the good short irons, some good middle irons today, made some good putts."
Bob Tway also shot a 65 to grab a share of second place with Jeff Sluman, who posted a 6-under 66, at 10-under 134.
David Frost (67) sits alone in fourth place at minus-9, while two-time winner this season Bernhard Langer (69), Steve Pate (69), Mark Calcavecchia (69) and Tom Lehman (66) are tied for fifth at 8-under.
Stadler started on the back nine and began his move up the leaderboard with his first of four sets of back-to-back birdies at the 11th and 12th, which he capped by holing out from a bunker.
"I was in the right bunker about probably from here to the back of the media room next door, 40 feet, 50 feet maybe. Just got it up over the lip, trickled down. Actually it trickled right in barely," Stadler said about the 12th.
He turned the trick again at the 15th and 16th before stumbling to his lone bogey of the day at the 18th, dropping him to 8-under for the tournament.
Stadler bounced right back with consecutive gains at the first and second, and then followed three straight pars with his final pair of birdies at the sixth and seventh to reach 12-under.
He closed with a couple of pars to remain there.
After following an opening par with a birdie at the second, Tway reeled off seven straight pars before pouring in an eagle at the par-5 11th to move to 6- under.
He then ended his round with four birdies over his final five holes to close out his 65 and finish two strokes behind Stadler.
Sluman bogeyed his first hole, the 10th, but bounced right back with back-to- back birdies at the 11th and 12th.
He poured in another pair of birdies at the 15th and 16th to make the turn at 7-under.
He dropped a shot at the first before running off four straight gains from the third to meet Tway at 10-under. Sluman then parred his last three holes to end there.
"I just drove it good. And from there, the golf course certainly isn't easy, but with all the rain and that, the greens were very receptive if you keep it in the fairway and I did that today and obviously made a few putts," Sluman said.
Frost had earlier met Tway at 10-under with birdies at Nos. 13, 16, 1, 2, 3 and 5, but tripped to a bogey at the seventh and parred his final two holes to finish three shots off the pace.
NOTES: The first round was completed Saturday morning after being suspended due to darkness Friday ... The course record is 64 and was set by Tom Hoag in 2010 ... Stadler has not held the 36-hole lead at a 54-hole event since the 2004 SAS Championship, which was his last win ... Stadler is seeking his ninth win on the Champions Tour ... Only three of nine 36-hole leaders have won this season on the Champions Tour.