In the only team event on the PGA Tour, Sunday's final round became a battle between Australia and South Africa and required more than 72 holes to decide a winner.
Cameron Smith sank a par putt on the first playoff hole and he and teammate Marc Leishman clinched victory at the Zurich Classic of New Orleans, besting 54-hole leaders Louis Oosthuizen and Charl Schwartzel.
Both teams finished the final round at 20 under, with each side missing a birdie putt on the 18th green. They headed back up to the 18th tee to begin the playoff, where Oosthuizen, playing first, watched his tee shot take a right turn into the water.
The Oosthuizen-Schwartzel team took a penalty stroke and left the door wide open for Leishman and Smith, who went on to win with a two-putt par.
It was Smith's second win at the Zurich Classic; in 2017, he and Jonas Blixt won the first edition of the tournament in the team format. All three of Smith's career wins on the PGA Tour have come in playoffs.
The Australians entered Sunday one stroke behind Oosthuizen and Schwartzel and played alongside them in the final group of the day. Leishman-Smith jumped out to a two-stroke lead on the back nine on their way to carding a 2-under 70. Oosthuizen-Schwartzel posted a 71.
A bogey on No. 10 for the South Africans and a birdie by the Australians the following hole shook up the leaderboard, with Leishman-Smith moving to 22 under and a two-shot advantage.
Leishman's tee shot on No. 13 nestled under the famous cypress in the middle of the fairway. Smith took a drop and later sank a 7-foot, 9-inch bogey putt to limit the damage. At the same time, Schwartzel missed a makeable birdie opportunity that would have drawn the teams even.
But a two-stroke swing eventually occurred on No. 15. Schwartzel redeemed himself by making a birdie of nearly 15 feet while Smith missed a par, and the teams switched places on the leaderboard, with the South Africans returning to 21 under.
Leishman and Smith birdied No. 16 to tie the lead again and both teams made bogey on the tough par-3 17th, eventually leading to the playoff.
Richy Werenski and Peter Uihlein of the U.S., the only team to score in the 60s all four rounds, finished 19 under for third place. Three more teams of Americans tied for fourth at 18 under: Billy Horschel-Sam Burns, Keith Mitchell-Brandt Snedeker and Keegan Bradley-Brendan Steele.
The teams played best ball in the first and third rounds and alternate-shot foursomes in the second and fourth rounds.