Lunde finished 54 holes at 7-under 206 and is one clear at The Ohio State University Scarlet Course.
Josh Broadaway also posted a 4-under 67 on Saturday and is tied for second place with Scott Gardiner, who carded a 68 in round three. The pair is knotted at minus-6.
Brendon de Jonge shot a 2-under 69 and is alone in fourth at 5-under 208.
Bob May, who lost the 2000 PGA Championship in a playoff to Tiger Woods, posted a 67 and is tied for fifth with overnight leader Peter Tomasulo, who only managed a 1-over 72. The duo is in at 4-under 209.
Lunde birdied the par-4 second, but lost a stroke with a bogey at the par-3 fifth. It was his play right after making the turn that vaulted Lunde atop the leaderboard.
At the 10th, Lunde hit a 9-iron to 10 feet to set up birdie. He saved a nice par at 11, then hit a 5-iron to 30 feet with his second at the par-5 12th. Lunde holed that to reach 6 under, then followed that up with a 10-footer for birdie at No. 13.
Lunde parred out for the 54-hole lead as he tries to get his first Nationwide Tour victory.
'It's the same thing no matter what you're doing because even if you're in 20th or first or 50th, you still want to play good on Sunday and a get chance to make a good check with a good round if you're back in the pack or if you're at the top,' said Lunde, who is 28th on the Nationwide Tour money list.