SEOUL (REUTERS) - American Justin Thomas birdied the second extra hole of a play-off against Marc Leishman to win the PGA Tour's US$9.25 million (S$12.6 million) CJ Cup at the Nine Bridges Golf Club on Jeju island on Sunday.

Both players finished on nine-under 279 for the four rounds of the Tour's first regular-season event in South Korea after carding 72 and 70 respectively.

That was a shot better than Cameron Smith (70) in third, with home hope Kim Whee (72) in fourth spot, two strokes further back on six-under.

After Leishman and Thomas carded matching pars at the first extra hole, the 18th, the Australian leaked his second shot into the water right of the green as they came down the par-five closing hole for a third time on Sunday.

Despite seeing his opponent's ball splash down in the lake, Thomas opted against laying-up and kept faith with a wood, battering his second from 243 yards just short of the green.

The FedExCup champion's eagle putt would come up short but his birdie was more than enough to beat Leishman, who finished with a bogey six.