Donald overcame a double bogey and bogey on the front nine to catch Furyk with birdie on the 16th hole. The Englishman finished 11-under 202.
Furyk held the lead for much of his back nine at Harbour Town Golf Links, but made bogey on the closing lighthouse hole for 69 to drop back.
Brendan de Jonge (66) and Scott Verplank (67) are two shots behind at 9-under.
Donald is third in the world behind top-rated Martin Kaymer and No. 2 Lee Westwood. But Donald would claim the top spot with a victory at Harbour Town.