"Yeah, bridesmaid again unfortunately but I played okay today," Donald, 38, told Golf Channel after carding a level-par 71 on the Harbour Town course at Hilton Head Island to finish two shots behind winner Branden Grace of South Africa.
"Just a couple of putts wouldn't quite go in and, as I expected, someone played well. That was a great round from Branden.
"I guess next year I've got to try and be about three or four (shots) back going into Sunday, that seems to be the sweet spot," grinned Donald, who has not triumphed on the PGA Tour since the 2012 Transitions Championship.
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Grace had trailed Donald by three strokes after 54 holes.
For Donald, his week at Harbour Town represented excellent progress. He considered quitting professional golf just 11 months ago after a protracted form slump.
"This is my best finish this year," said the five-times PGA Tour winner, who had previously recorded just one top-25 in 10 starts on the circuit this season, a tie for 22nd at the Valspar Championship last month.
"So this is a great step in the right direction. I am really positive about my game going forward and I am pretty positive about the way I handled it today.
"I didn't quite get it done but I am excited about playing next week," said Donald, referring to the April 21-24 Texas Open.
He arrived at the Heritage ranked 95th in the world, but is projected to jump nearly 30 spots.
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Andrew Both)
