The 53-year-old Lehman will be seeking his third major Champions Tour title after putting together a 10-under 206 total going into the final round.
He bested Peter Senior in a playoff to win last year's event at Shoal Creek, and will again face a challenge from him -- Senior matched the low round of the week with his 6-under 66 Saturday.
Senior forged a second-place tie with Jeff Sluman (70) at minus-8.
Bill Glasson, who held the second-round lead, tumbled to a 2-over 74, falling into a share of fourth place at 7-under 209 with two-time champion Fred Funk (71), Russ Cochran (72) and Brad Bryant (71).
Swim Week Miami Beach 2014 [PHOTOS]