He shot a 1-under 69 in the third round and has the lead at 1-under-par 209 as Wadkins is the only player under par in the field. This marks the first time since the tournament shifted to a 72-hole format that only one player was under par after 54 holes.
Roy Vucinich shared low of the day honors with Bob Eastwood Saturday with a 2-under 68. Vucinich is tied for second place with Fuzzy Zoeller and Larry Nelson at even-par 210.
Walter Hall and club professional Jay Overton are tied for fifth at 1-over-par.
Wadkins and Zoeller, playing in the same group, shared the lead at 3-under-par when they reached the par-5 16th tee. Wadkins pushed his tee shot deep into the trees on the right side but found an out and advanced his ball down the fairway. Zoeller was in the fairway off the tee and laid up short for his second shot.
Their third shots proved to be critical. Wadkins left his 25 feet short and right of the hole, safely on the green. Zoeller flew his over the putting surface and left himself with an impossible chip that rolled 20 feet past the stick.
Wadkins blew his putt four feet past but made the improbable par save. Zoeller ran his par putt three feet past the hole and then missed his short bogey save. Zoeller left with a double-bogey-7 while Wadkins headed to 17 with a two-shot lead.
'That hole just plays short,' said Zoeller, referring to 16. 'And I know it. I'm a big dummy. It always plays short and I just nuked it a little bit too hard. Once I knocked it over the green, I was a piece of dead meat hanging from a meat pole.'
Wadkins drove into a fairway bunker at the 17th and nicked the lip of the trap advancing it only 50 yards. His third was in deep rough but he wedged a shot from 94 yards that rolled a foot from the stick. Wadkins tapped in the par save and Zoeller made par as the margin remained the same.
The 18th hole saw another erratic drive from Wadkins, this one landing in the left rough under a tree. He had no other shot but a punch into the fairway but needed to get under the ball enough so that it would not get stuck in the rough. Wadkins did not get under it and left his ball in the left rough.
Wadkins' third shot came from deep rough and also had a tree blocking his path to the flag. He hit it short into the left rough and needed three more strokes to get into the hole. Wadkins took a double bogey to fall to 1-under par for the tournament.
Zoeller hit another approach long at 18, landing in the back bunker. He left the 18th with a bogey and an even-par 70, meaning he would start Sunday's round one shot behind Wadkins.
'I just hit a bad tee shot,' said Wadkins, speaking about 18. 'You can't miss it left and you can't miss it right. I just didn't make a good swing. I was a little short. I just didn't do what I needed to do.'
Despite stumbling home Wadkins said there would be no holdover effect from the poor finish on Sunday.
'It's over now. The hole is finished,' said Wadkins, the younger brother of fellow Senior Tour member Lanny Wadkins. 'I'm damned close enough to win tomorrow, so that's all that counts. You're going to have a bad hole now and then. You just hope it's not the 72nd hole.'
Wadkins has enjoyed success since joining the Senior Tour in the middle of 2001. He has one victory and 11 top-10 finishes in 24 starts.
Wadkins went 1-under-par through the front nine and made his move up the leaderboard on the back side. He drained a 10-foot birdie putt on 11 and played a beautiful approach four feet from the hole at 14 to set up another birdie and tie him for the lead with Zoeller and second-round leader Wayne Levi.
Zoeller played steadier than anyone before his late-round collapse. He birdied five and seven and found a greenside bunker at the 14th. Zoeller blasted out and saw the ball roll a few feet before falling into the cup for a birdie and a share of the lead.
Zoeller, a tour rookie, is in search of his first win on the elder circuit and thinks he has a low round in him Sunday.
'I wish I could hit them all good,' said Zoeller. 'Maybe tomorrow is the day that I'll do that. I came very close today. I drove the ball well, I hit the ball well except for a few screwy shots coming in.'
Levi stumbled home with a pair of double-bogeys and a bogey on the back nine. He shot a 5-over 75 and is tied for seventh with Bob Gilder, John Schroeder, Tradition champion Jim Thorpe and three-time Senior PGA Champion Hale Irwin. The group stands at plus 2.
Full-field scores from the Senior PGA Championship