Lehman ended at 16-under-par 200, racking up his second Champions Tour victory of the year and fourth in his career.
Lehman carded five birdies and two bogeys to finish well ahead of three competitors at Fallen Oak.
Sluman began the day one shot behind Lehman but double-bogeyed the final hole.
Sharing fifth at minus-11 were Olin Browne (67) and Jay Haas (68).
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