Luke Donald shot a 2-under 69 on Saturday to take a one-stroke lead in the RBC Heritage on Saturday, while top-ranked Jason Day had a season-worst 79 to fall nine shots back with one round left.
Day, tied for the lead entering the round, has won two of his past three PGA Tour events and figured to contend at Harbour Town. Instead, the Australian made eight bogeys and a double bogey.
Donald had a 7-under 206 total.
Jason Kokrak and Charley Hoffman were a stroke back. Kokrak shot a 68, and Hoffman bogeyed the closing lighthouse hole for a 71.
Now, Donald looks to end his hard-luck history at Harbour Town. The Englishman has five top-three finishes without a win.