Los Angeles - South Korea's Kang Sung fired seven birdies in a four-under par 67 on Sunday to claim his first US PGA Tour victory, a two-shot win over Matt Every in the Byron Nelson in Dallas, Texas.

Kang drained a 23-foot birdie putt at 15 to take the lead for good on a marathon day that saw the leaders play 27 holes thanks to the six-hour weather delay on Saturday.

Kang, who equalled the Trinity Forest course record with a bogey-free 10-under 61 on Friday, finished with a 23-under par total of 261.

Every had edged ahead by one through nine holes when darkness halted play on Saturday.

But Kang fired three birdies and bogey over the final nine holes of the third round to regain a three-shot lead.

Every responded with seven birdies - including five on the front nine - in a five-under par 66 in the fourth round.

But he was unable to maintain the lead and his 21-under total of 263 was only good enough for a share of second place alongside compatriot Scott Piercy.

Piercy capped a bogey-free tournament - the first on the US PGA Tour since 2010 - with a seven-under 64.

Kang strung together three straight birdies at eight, nine and 10. He was unable to get up and down from a green side bunker at the 12th, but he reeled off another trio of birdies at 14, 15 and 16 to move to 24-under for the tournament.

He was three strokes up when he arrived at 18, where his closing bogey proved immaterial.

"I'm so happy right now," Kang said after notching his first tour win in his 159th start.

"Yesterday we finished too late," Kang said. "I didn't have time to sleep much, only slept about three hours."

Because he knew it would be hard to concentrate, Kang said he told his caddie "I just wanted to be chill and having some fun and then when my turn came just try to really focus in -- and it worked out great."

World number three Brooks Koepka finished strong, carding a six-under par 65 to finish alone in fourth on 20-under 264 heading into his PGA Championship title defence at Bethpage Black next week.

Leading final-round scores on Sunday in the US PGA Tour's Byron Nelson tournament in Dallas, Texas (par-71, USA unless noted):

261 - Kang Sung (KOR) 65-61-68-67

263 - Matt Every 65-65-67-66, Scott Piercy 67-69-63-64

264 - Brooks Koepka 65-66-68-65

267 - Peter Uihlein 69-71-63-64, Kiradech Aphibarnrat (THA) 69-68-66-64, Rory Sabbatini (SVK) 67-65-68-67, Tyler Duncan 64-66-70-67, Matt Jones (AUS) 65-70-65-67

268 - Justin Harding 66-73-64-65, Sebastian Munoz 69-66-65-68

269 - Pat Perez 67-71-67-64, Carlos Ortiz (MEX) 69-69-66-65, Padraig Harrington 69-69-66-65, Nicholas Lindheim 70-69-62-68, Doug Ghim 69-66-66-68

270 - Vaughn Taylor 69-67-68-66, Kramer Hickok 65-73-66-66, Stephan Jaeger (GER) 69-66-67-68

271 - Jonas Blixt (SWE) 65-70-70-66, Henrik Stenson (SWE) 67-69-66-69, Shawn Stefani 65-72-64-70