South African Rory Sabbatini stands alone in second place at 6-under-par 66.
Three-time champion Tiger Woods shares 13th place at 3-under-par 69. Woods got off to a steady start with 10 straight pars to open his round. He then birdied three of his next five holes. The 29-year-old parred his final three holes to close a bogey-free round of 69.
'With the wind blowing like this, I'm extremely happy with my start,' Woods said. 'I made no bogeys, three birdies and that's it. You've got to make putts. Some of the pin locations are accessible. You just kind of plod along, wait your turn.'
Sluman first got on the board with a birdie at the par-3 fourth. He came back with a 2-foot birdie putt on No. 6 at Muirfield Village Golf Club. The 1988 PGA Championship winner chipped in for birdie on the eighth.
The 47-year-old made it two straight as he sank a birdie putt on the ninth to make the turn at minus-4. Sluman capped a run of three straight birdies as his 20-foot putt at the 10th fell into the cup.
Sluman then birdied the 12th from 40 feet out, his third birdie on a par-3 in the first round. After a pair of pars, the Florida State alum ran in a 6-foot birdie putt on the 15th to move into the lead at 7 under. The six-time winner on the PGA Tour parred his final three holes, including an up-and-down par at the last to maintain a one-shot cushion.
'The golf course is in terrific shape. It's the best I've ever seen it,' said Sluman, whose best finish this year was a tie for ninth at the Pebble Beach National Pro-Am. 'It was a lot of fun out there. Obviously I was pleased with how I played today.'
Sluman leads after one round for the 13th time in his career. However, of those previous 12 events, he has never went on to win.
Sabbatini dropped a sand-wedge within 4 feet to set up a birdie on the third to get his round going. The South African scrambled to a birdie on the par-5 fifth.
He sank a 12-foot birdie putt at the next to move to 3 under. Sabbatini made it three in a row as his 5-foot birdie putt on the seventh found the bottom of the cup.
Sabbatini rolled in a 15-footer for birdie at the 10th to get to 5 under. He sank an 18-foot birdie putt at 17 and parred the last to close a bogey-free round of 66.
'The wind was just kind of swirling out there, making conditions a little tougher, and you really had to settle into each shot as it came,' Sabbatini said. 'You really needed to decide on what the wind was doing and go with that and really trust it.'
Ian Poulter and Tim Herron are tied for 11th at 4 under par.
Woods was joined at minus-3 by 14 other players. Among that group are two-time champion Kenny Perry, British Open winner Todd Hamilton and Byron Nelson Championship runner-up Sean O'Hair.
Defending champion Ernie Els struggled to a 1-over-par 73. He stands in a tie for 61st. Tournament host Jack Nicklaus posted a 3-over-par 75. World No. 1 Vijay Singh shot a 5-over-par 77.