Hank Kuehne shot a 4-under 67 to share second place with Craig Bowden and Richard S. Johnson. Robert Damron and Jeff Brehaut followed at 11-under-par 202.
With amateur Michelle Wie out of the picture, after the teenager was the focal point of the tournament for the first two rounds, Lewis got back to business on Saturday. He found trouble early with a bogey at the par-4 first.
Lewis steadied himself and ran off five consecutive pars before picking up the first of back-to-back birdies at the par-3 seventh. Lewis looked to be in trouble at the par-3 12th after his tee shot found a greenside bunker, but he blasted out of the sand within a foot of the hole to save par.
The 44-year-old kept racking up pars at the 13th and 14th holes. At the par-4 15th, Lewis played his second shot inside 30 feet and ran home the long birdie try to get to 15 under.
Lewis found a fairway bunker off the tee at the par-4 closing hole, but hit a tremendous second shot that landed near the hole, but ultimately rolled away from the cup. Lewis two-putted for par to take a three-shot advantage with one round to play in search of his first victory since the 2003 84 Lumber Classic of Pennsylvania.
'I didn't make as many short putts as I probably should have, but I felt like I had my game going pretty good,' Lewis said. 'I struck the ball okay and I felt like I hit it kind of where I wanted to most of the day.'
Kuehne bogeyed the first, but responded with a birdie at the par-5 second. He collected back-to-back birdies from the fifth, but gave a shot back with a bogey at the seventh.
He stumbled to another bogey at the 11th, but picked up four birdies over his next six holes to finish within three of Lewis.
Johnson jumped out of the gate with an eagle at the par-4 first. He suffered bogeys at the third and sixth holes, but countered with a birdie at the seventh. The Swede birdied the par-5 10th and reached the green in two at the par-5 17th. His eagle try hit a spike mark and skirted just right of the hole. Johnson tapped in for birdie on his way to a 68.
'I was just expecting it to go to the middle of the hole, and then all of a sudden, for some reason it just broke a little right and it just hung out on the right lip,' Johnson said of his putt on the 17th. 'I couldn't believe it.'
Bowden parred his first eight holes, but tallied back-to-back birdies starting at the par-4 ninth to reach 11 under around the turn. Bowden added a birdie at the 17th for a 68 of his own.
'I've been playing pretty well,' said Bowden. 'I feel pretty good about my game right now, hitting it really solid. I didn't capitalize on some of my opportunities today, but I'm still in decent shape for tomorrow.'
Zach Johnson has struggled since his last top-10 finish this season at The Players Championship, but the 29-year-old fired a 66 to move into a tie for seventh place with Shigeki Maruyama, Carlos Franco, Joey Snyder III and Sean O'Hair at 10-under-par 203.