* Almost squanders another shot at victory
* Donald narrowly misses chip at last hole (Adds detail, quotes)
April 20 (Reuters) - American Matt Kuchar ended a frustrating run of close calls in spectacular style when he holed a bunker shot on his final hole to win the RBC Heritage in South Carolina on Sunday.
Minutes after three-putting the 17th from four feet, Kuchar responded emphatically by sinking a 20-yard sand shot for birdie at the par-four 18th to beat third round leader Luke Donald by one stroke at Harbour Town on Hilton Head Island.
"I wish it wasn't that great a finish but I made it that way after 17 and, man, that was so thrilling to see that ball disappear," said Kuchar, in a green side television interview. "To hole the bunker shot in that fashion is something I'll never forget. That was a full-on Augusta National roar (from the gallery)."
Kuchar carded a seven-under 64 to finish at 11-under-par 273, collecting $1.044 million for his seventh PGA Tour win.
He had been in contention in the final round the previous three weeks, finishing no worse than fifth, but had stumbled down the stretch, most notably at the Houston Open, where he bogeyed the last and lost a playoff.
The 35-year-old looked to have squandered another chance after missing a four-footer and a two-footer at the penultimate hole.
"It was blowing pretty hard on that green. I tried to play it straight (and) it went a little left," said Kuchar of his first putt. "I know that's not a characteristic of mine to three-putt from four feet (and) I wanted to have another chance."
Donald, meanwhile, narrowly missed a 30-yard birdie chip at the last and was left to rue another near-miss at Harbour Town, where he has finished second or third five times in the past six years.
Americans Ben Martin (67) and John Huh (68) finished one shot further back in a tie for third.
Donald started the day with a two-shot lead and shot 69, but it was not enough for the former British world number one, who double-bogeyed the par-four sixth after hitting his tee shot out-of-bounds.
"I caught a gust there and took me right out of my rhythm and (hit a) big snap hook," Donald said. "I hit a poor tee shot (into a water hazard) on 10 and would love to have given myself a better chance on 18 but other than that I hit a lot of solid shots."
With his victory, Kuchar joins an illustrious list of champions at Harbour Town that includes Jack Nicklaus, Arnold Palmer, Tom Watson, Payne Stewart, Nick Faldo and Greg Norman.
"To put my name on a list of champions here, that is so great," Kuchar said. "This means a lot to me." (Reporting By Andrew Both in Cary, North Carolina. Editing by Steve Keating.)