Webb Simpson claimed his second PGA Tour victory of 2020 with a one-stroke win at the RBC Heritage on Sunday.

The American carded a seven-under 64 in the final round at Harbour Town Golf Links in South Carolina to add to his success at the Phoenix Open in February.

Simpson, the 2012 U.S. Open champion, has won multiple times in the same year for the first time since 2011.

The runner-up at the tournament in 2013, Simpson made five birdies in a six-hole stretch on the back nine, with the final round having been stopped for almost three hours due to weather.

Simpson broke Brian Gay's tournament-record score of 20 under set in 2009 with his 22-under 262.

"It was a crazy day. Honestly, I'm speechless right now," Simpson told CBS.

"It looked like we weren't going to finish, but we went back out, the Tour did a great job of getting us out there pretty quickly, we only had a 20-minute warm-up and it was a long day on the golf course as well.

"I didn't really get it going until 12 and then the putts started going in and I was getting confident and it's amazing to be standing here right now."

Simpson finished one shot clear of Abraham Ancer (65), while Daniel Berger (65) and Tyrrell Hatton (66) were tied for third at 20 under.

Sergio Garcia (65) and Joaquin Niemann (65) were tied for fifth at 19 under, a shot ahead of Brooks Koepka (65).

Justin Thomas and Dylan Frittelli surged with brilliant rounds of 63 and 62 respectively as they ended up in a six-way tie at 17 under.

World number one Rory McIlroy endured another difficult Sunday, posting a one-under 70 to finish tied for 41st.