Washington - Japan's Satoshi Kodaira birdied the third playoff hole to defeat South Korea's Kim Si-woo and win the Heritage tournament on Sunday for his first PGA Tour victory.
The 28-year-old from Tokyo had won six times on the Japan Tour, most recently at last November's Taiheiyo Masters, but captured the biggest title of his career with a birdie at the par-3 17th at Harbor Town in Hilton Head, South Carolina.
World number 46 Kodaira was coming off his best major showing, and what had been his top US result, with a share of 28th at last week's Masters.
Kim and Kodaira both finished 72 holes at 12-under-par 272, one stroke ahead of Americans Luke List and Bryson DeChambeau with Billy Horschel and Webb Simpson on 274.
Kodaira and 51st-ranked Kim began the playoff by replaying the 18th hole. Both parred twice more as they had in the final round, forcing the showdown to a third extra hole, the par-3 17th.
Both had made bogeys at 17 in the final round but Kodaira solved the tricky hole for the victory.
Kim, 22, was denied his third PGA title after wins in 2016 at Greensboro and last May at the Players Championship.
Kodaira, who shot 63 Friday, fired a final-round five-under-par 66 to charge into the hunt. He opened with three birdies, began the back nine with another then sank birdie putts of 28 feet at the par-3 14th and 10 feet at the par-5 15th but missed the 17th green and made bogey.
He still needed the leaders in the final group to back up and that's what they did, Kim firing a par 71 while List shot 72 and 54-hole leader Ian Poulter of Britain closed on 75 - threesomes being used in a bid to finish before predicted storms arrived.
Kim blasted out of greenside bunkers to within five feet to birdie the par-5 second and fifth holes, then holed out from 22 feet at the ninth to make the turn on 15 under.
But Kim stumbled with bogeys at the par-4 12th, missing an 11-foot par putt, and par-5 15th, where he never found the fairway and missed a 4-footer for par, leaving him only one stroke ahead of List and Kodaira.
Kim missed a 5-foot par putt at the par-3 17th for a bogey that dropped him level with Kodaira as he reached the 18th green.
List had bogeys on three of his prior four holes but blasted out of a bunker at 17 and made a 4-foot par putt to stand one back entering 18.
List dropped his approach 10 feet from the cup but missed his birdie putt to miss the playoffs.
Kim placed his approach six feet from the cup but missed his birdie putt, setting up the playoff.
Poulter saw his title hopes collapse with five bogeys on the back nine, fading at the end of his sixth consecutive week of playing to a final-round 75.
The 42-year-old Englishman missed the 10th green on his approach to set up a bogey, then missed an 8-footer for par at 13 and found water off the tee at the par-3 14th for back-to-back bogeys, which he also had at 16 and 17.
Poulter, who won the Houston Open two weeks ago to earn a Masters berth, shared seventh with Americans Bill Haas, Kevin Streelman, Patrick Cantlay, Chesson Hadley and Kevin Kisner and South Korea's An Byeong-hun on 275.
Leading scores after Sunday's final round of the US PGA Tour RBC Heritage at Hilton Head, South Carolina (USA unless noted, par 71, Kodaira wins playoff with birdie on third extra hole):
272 - Satoshi Kodaira (JPN) 73-63-70-66, Kim Si-woo (KOR) 68-65-68-71
273 - Bryson DeChambeau 68-64-75-66, Luke List 70-64-67-72
274 - Webb Simpson 69-68-69-68, Billy Horschel 66-69-67-72
275 - Kevin Streelman 70-70-67-68, Patrick Cantlay 67-72-68-68, Bill Haas 69-66-71-69, An Byeong-hun (KOR) 73-67-66-69, Chesson Hadley 66-68-69-72, Kevin Kisner 69-68-66-72, Ian Poulter (ENG) 69-64-67-75
276 - Matthew Fitzpatrick (ENG) 69-71-69-67, Jonas Blixt (SWE) 67-73-67-69
277 - Beau Hossler 70-69-70-68, JJ Henry 72-69-69-67, Scott Piercy 71-65-71-70, Dustin Johnson 69-69-72-67, Ted Potter Jr 72-66-69-70, Emiliano Grillo (ARG) 72-66-69-70, Ryan Moore 69-69-67-72
278 - Tyrone Van Aswegen (RSA) 73-69-66-70, Bud Cauley 71-68-71-68, Charley Hoffman 72-69-66-71, Brian Harman 70-68-69-71, Brandt Snedeker 70-64-72-72, Matt Kuchar 66-70-69-73, Rory Sabbatini (RSA) 64-70-70-74, C.T. Pan (TPE) 70-65-67-76