'I'm tickled with the way I've been playing,' said Cink, who won this tournament in 2000. 'I've been keeping the ball in play most of the way and I'm managing my game really well. I'm playing with a lot of peace and a lot of confidence. It's really turned into some low scores.'
Woody Austin (65) and Kenny Perry (67) share third place at 10-under-par 203.
Hal Sutton, the 2004 United States Ryder Cup captain, held a two-shot lead midway through the round Saturday but a costly double-hit chip at the 14th cost him a penalty stroke and dropped him to a round of even-par 71. He shares fifth with four-time Heritage champion Davis Love III (69), Steve Flesch (67) and Chad Campbell (70) at minus-9.
Cink was not making up any ground on Sutton, who reached 12-under with back- to-back birdies at six and seven. Cink dropped a shot at the seventh but got his round going at the eighth when he putted in from off the green.
Cink birdied the par-4 10th and made it two in a row with a long birdie putt at the 11th. At 12-under par and alone in the lead, Cink made a mistake off the tee at No. 12 as his 3-wood tee ball did not get far enough down the fairway to avoid hanging tree branches in his approach. He hit a low 5-iron from 148 yards that ran through the putting surface into the rough. Cink flopped his pitch five feet right of the hole but missed the par save and fell back to 11-under par.
Sluman was already in the clubhouse at 11-under par so it was up to Cink to take the lead on his own. At the 15th, Cink hit a long pitching-wedge that sailed over the green. He hit a poor pitch that stopped seven feet past the hole but Cink, a three-time All-American at Georgia Tech, calmly holed the putt to save par and stay with Sluman at minus-11.
Cink elected to hit driver off the 16th tee and the ball headed into a bunker on the left side. The ball skipped through the sand and into the fairway, where Cink played his approach to four feet. He drained the birdie putt to go one ahead of Sluman.
Cink had reasonable chances at birdie on the final two holes but settled for pars and the fifth 54-hole lead in his career. He has not netted a victory in the previous four occasions with the lead and his most recent loss with the 54-hole lead was his most famous.
At the 2001 U.S. Open, Cink could have been a part of the 18-hole playoff between eventual winner Retief Goosen and Mark Brooks. At the 72nd hole on Sunday, Cink thought Goosen had an easy chance to win the title so Cink failed to take his time on a short putt. He missed the putt but Goosen missed an equally short putt and Cink missed out on his best chance at a major championship.
Cink struggled in 2002 after making his first Ryder Cup team and coming close to his first major. He posted only four top-10s last year and finished 73rd on the money list with less than $1 million for the first time since 1998.
'I got into a funk where I was result oriented,' said Cink, a two-time winner on tour. 'I was so concerned with making mistakes that I wouldn't allow myself to be free. I really learned how to free it up quite a bit more now and it's just a lot more fun to play this way.
'It's a tough game if you're afraid of failure. There's roughly 140 losers every week and one winner. You play a great career in golf and you win four or five times, maybe. You have to learn to accept it.'
Sluman was flawless on Saturday with seven birdies and no bogeys. He collected three birdies on his front nine but flew up the leaderboard with his play on the back nine.
Sluman, who lost a playoff in this event to Glen Day in 1999, holed a downhill 12-footer at the 12th and made it two birdies in a row with a four-footer at No. 13.
At the 14th, Sluman hit a 5-iron 35 feet left of the hole and drained the long birdie putt to get to 10-under par.
'It's just one of those ones that just goes in and you have no explanation for it,' said Sluman.
Sluman ran home an eight-foot birdie putt at 15 to make it four in a row. He had a six-foot look at birdie on the 16th but missed and his birdie try from 15 feet at the next grazed the hole without falling.
'Historically, every week, somebody makes a big run on Saturday and I felt as if I was playing well enough that I could make a few putts and maybe I could be the guy to shoot a good number here and I've done it in the past,' said Sluman. 'I went out and stayed pretty patient and made a few putts.'
Sutton missed the green left at the par-3 14th and double hit his chip shot. He called the one-stroke penalty on himself and double-bogeyed the hole but is still in contention for his first title since the 2001 Houston Open.
'That's the right thing to do and I've got to get up and look at myself in the mirror tomorrow,' said Sutton, referring to his penalty. 'I lost it in the middle of the round. I didn't do the same thing I've been doing.'
Ernie Els, Nick Price, Jim Furyk, Chris Riley, Doug Barron, Peter Jacobsen, Tom Pernice, Jr., Matt Gogel and Geoff Ogilvy are tied for ninth place at 8-under-par 205.