Tyrrell Hatton shot a final round 66 but finished two shots behind Webb Simpson, who won with a tournament record low score of 22 under.
-22 Webb Simpson
-21 Abraham Ancer
-20 Tyrrell Hatton, Daniel Berger
-19 Sergio Garcia, Joaquin Niemann
-18 Brooks Koepka
-17 J. T. Poston, Michael Thompson, Bryson DeChambeau, Justin Thomas, Dylan Frittelli, Ryan Palmer
Final round report
Webb Simpson claimed the PGA's RBC Heritage event with a tournament record score of 22-under 262.
The American was untouchable down the stretch at Hilton Head, South Carolina on Sunday, claiming five birdies on the back nine to finish with a seven-under 64.
Simpson's stellar closing run proved to be just enough to edge out Mexico's Abraham Ancer, who finished one shot back at six-under 65.
The win lifted Simpson to number five in the world, following his victory at the Phoenix Open in February.
England's Tyrrell Hatton, who went into round four with a share of the lead, was ultimately forced to settle for third alongside America's Daniel Berger.
After steaming into contention with an eight-under 63 on Saturday, Hatton was left to rue a wayward tee shot on the 13th which led to a bogey.
A birdie on the 16th then proved too little for the 28-year-old to compete with Simpson's blemish-free back-nine performance.
Meanwhile world No 1 Rory McIlroy closed out another lacklustre tournament with a one-under 70 on Sunday to tie for 41st place at 11-under.
After bouncing back from a disappointing opening day with a 65 and 66 on Friday and Saturday, McIlroy quickly dropped out of contention on Sunday thanks to a double bogey on the fourth.
The result marks the second tournament in a row that the Northern Irishman failed to finish in the top 30.
Britain's three other competitors fared slightly better, all finishing tied for 14th.
Justin Rose closed out the tournament strongly with a six-under 65 while Ian Poulter and Matthew Fitzpatrick both shot 68 on Sunday to join him at 13-under.
The PGA Tour continues on Thursday with the Travellers Championship from TPC River Highlands in Connecticut.
Third round report
Tyrrell Hatton crafted a blemish-free round of 63 to join a group of four at the top of the leaderboard ahead of the final round at the RBC Heritage.
The Englishman had four birdies inside the first five holes and reached the turn at five under.
He then picked up another three shots before finishing his round off with a 24-foot birdie putt.
The eight-under round follows a seven under on Friday and saw him move 21 places up the leaderboard where he sits tied with Abraham Ancer, Ryan Palmer and Webb Simpson.
Simpson, the overnight leader, could not follow up his opening scores of 65 and carded a 68 on Saturday, mixing four birdies and a bogey.
The leaderboard at Hilton Head in South Carolina remains tight with 17 players within three shots of the lead ahead of Sunday's final round.
Carlos Ortiz, who started the tournament with a pair of bogeys, shot a 63 to be part of a trio sitting a shot behind the leaders, while Ian Poulter and Matthew Fitzpatrick are tied for eighth on 13 under for the tournament.
World number one Rory McIlroy shot a third-round 66 to significantly improve his position.
McIlroy followed his second-round 65 with a five-under 66 to move to 10 under, and tied for 28th.
"I've been a little bit more decisive and committed off the tee in the last two days. Much better, I need to try keep doing that with the same game plan," he told the media after his round.
Dustin Johnson finished with 67, Brooks Koepka a 68 and Bryson DeChambeau a 70 as the Americans all sit tied for 16th on 12 under.
Second round report
Webb Simpson leads the RBC Heritage at the halfway stage but the action on the course was overshadowed by Nick Watney's positive Covid-19 test.
Simpson birded his last two holes to complete back-to-back rounds of 65 and hit the front on 12 under, one ahead of Bryson DeChambeau and Corey Conners, while 33 players were still on the course when play was suspended due to lightning storms in the area.
Rory McIlroy was safely in the clubhouse and safely through to the weekend on five under after he recovered from his opening 72 with a classy 65 with six birdies and no blemishes.
Simpson went quietly and efficiently about his business and he looks certain to enjoy the halfway lead on his own unless Matt Fitzpatrick can birdie the three holes of his round remaining when play resumes on Saturday morning.
Simpson's advantage could have been more commanding had he not carded three bogeys against his nine birdies around a tight and testing Harbour Town Golf Links layout that suits his "fairways and greens" strategy as the former US Open champion chases his second victory of the year after winning in Phoenix in February.
But DeChambeau proved that raw power can tame one of the more old-fashioned courses on the Tour schedule as he forged his way into contention for the second week running, recovering from a bogey at his opening hole with eight birdies, including six in eight holes on the front nine
DeChambeau, whose weight gain of around three stone in nine months has helped him propel his ball extraordinary distances over the first six rounds of post-shutdown tournament golf, signed for a 64 which earned him a share of second with Conners, the Canadian returning an eight-birdie 63 that was free of any blemishes.
Fitzpatrick was nine under with three holes to complete when play was suspended due to lightning storms in the area and, after a delay of two hours, he returned to birdie 16 and 18 either side of a bogey at the penultimate hole as he closed on 10 under.
Former world number one Brooks Koepka, who encountered an ailing Nick Watney in the car park on his arrival at the course in the morning, was just two off the lead when he rolled in his seventh birdie putt of the day at the 16th, although he bogeyed the last to slip to nine under alongside overnight joint-leader Ian Poulter.
The veteran Englishman was two over for the round and aware that a couple more mistakes would likely result in missing the cut, but he rallied late and birdied four of his last five holes to complete a commendable 69.
Ernie Els proved he can still compete on Tour despite turning 50 last October, the four-time major champion firing a second 67 to move to eight under alongside the likes of US Ryder Cup team-mates Dustin Johnson and Tony Finau, while Sergio Garcia and Bay Hill champion Tyrrell Hatton are a shot further adrift.
First round report
Ian Poulter claimed a share of the lead after shooting a seven-under round of 64 at the PGA’s RBC Heritage event.
Poulter had an early tee time at Hilton Head and took a liking to conditions, going blemish-free and finishing with a spring in his step by claiming four birdies after the turn.
The Englishman finished tied for 29th at last week’s Charles Schwab Challenge, the tour’s first tournament back after the coronavirus shutdown, and will start round two level with American Mark Hubbard.
The 44-year-old, who won the last of his three PGA titles in 2018, had shared his discomforting Covid-19 Test on Twitter on Wednesday, but will be glad he put himself through the process.
“Any time you shoot seven under par around this golf course, it’s obviously a pretty solid day,” he said.
“It’s very important being bogey-free. It’s a fiddly, testing, tricky golf course.”
He went on to reveal the surprisingly light load he taken on in terms of course practice during the pandemic shutdown, adding: “I played three or four rounds of golf in that spell of three months off, and it was apparent – as soon as I came back to hitting balls – I felt like I was swinging pretty good.
“I’m not one that plays round after round after round after round to feel that I need to be ready to play golf. I was super active, I was busy on social media, I was doing lots of different things around the house.”
World number one Rory McIlroy had a slow start, closing one over on 72. The Northern Irishman, who has questioned the wisdom of European players who have declined to travel, hit three bogeys along the way.
“I wasn’t particularly comfortable out there,” he admitted.
“I played here once before in ’09, and I just remember not being that comfortable around here then. It’s still sort of the same. I’m just not comfortable and sort of trying to pick lines and really commit to shots. I just wasn’t as committed as I need to be around here.”
There is a chasing pack of seven sitting one-shot back from Poulter and Hubbard, with Sheffield’s Matthew Fitzpatrick alongside Jordan Spieth on five under.
Spieth had a dicey start, including a triple-bogey at 12, but ended with a surge of momentum as he birdied seven times on the front nine.