Donald, who closed with a second successive level-par 71, needed to finish in the top eight at Harbour Town to retain top spot, but was last night well back in joint 43rd when he completed his round.
The Englishman lost a play-off to Brandt Snedeker at the same venue last year, but he was never in contention this time, following his opening-round 75.
Yesterday’s final round also started badly with a double-bogey six on the first, but birdies on the fifth and sixth helped Donald salvage some respectability. “Is it a concern? No,” Donald said. “Obviously, I’d have liked to have played a bit more consistently this year. I built it up nicely last year through tournaments and winning a bunch. As a result, there’s a little bit of fluctuation in the world rankings now.”
Speaking about yesterday’s final round, he added: “It’s a strange feeling when you get up early and don’t have a chance to win. It’s hard to get motivated on every round and every shot.
“You never know when you’re going to find something that might just click and make a difference.”
Sweden’s Carl Pettersson topped the leaderboard on 13 under par after three holes, three shots ahead of American Zach Johnson (through four).