Lee had seven birdies and a pair of bogeys in a 5-under 67 and is at 9-under 135 after 36 holes, tied with Rafa Cabrera-Bello, who had a final-hole bogey to finish his second round with a 68.
Danny Willett had a bogey-free 9-under 63 and jumped into third place at 8-under for the tournament. Ricardo Gonzalez shot 66 and is tied for fourth with Rory McIlroy and Thomas Bjorn, who each turned in second-round scores of 67, at 7-under 137.
Cabrera-Bello was tied with Matthew Baldwin and Romain Wattel for the first-round lead but Baldwin sagged to a 1-over 73 Friday and is tied for 12th at 4-under and Wattle was 3-over 75 in the second round and fell into a tie for 33rd.
Lee had an up-and-down front nine with three birdies against two bogeys. He pulled into the lead with three birdies over Nos. 10-13 and added another 17 at to get to 9-under for the tournament.
Cabrera-Bello played the second nine first and had bookend birdies at 10 and 18 around seven pars. Birdies at the first and second holes gave him three in a row before a bogey at the par-4 third.
Cabrera-Bello came back with a birdie at 4 and was alone in the lead after his birdie at the eighth but a bogey at No. 9 dropped him back into the tie with Lee.
Swim Week Miami Beach 2014 [PHOTOS]