Johnson birdied the 18th in regulation play, then again on the first extra hole to deny Australia's reigning Open champion Cameron Smith and South African Branden Grace on Sunday.

The victory was Johnson's second since he joined LIV Golf a year ago. He also won LIV Boston in a three-man play-off.

This one required some of Johnson's best stuff on the closing hole at rain-soaked Cedar Ridge for Johnson to take down a rampant Smith and Grace.

Johnson, who closed with a three-under-par 67, was trailing Smith (61) and Grace (65) by one when he hit his drive into the left rough on the 18th.

He was partially blocked by a tree but hit a sand wedge over the corner of the tree to 12 feet and made the birdie.

Smith was on the range waiting, having already birdied the 18th for his nine-under 61, tying Grace's LIV record in the opening round. Grace two-putted from 35 feet on the final hole, which put him in a play-off and assured his South African team 'Stinger GC' their first team win of the year.

RIGHT: Johnson claimed his second LIV Golf title ahead of next week's PGA Championship where he will be one of the favourites. PHOTO: Ian Maule/Getty Images.

All three players were roughly on the same line in the play-off, with Grace putting from the fringe. Grace missed to the left, Johnson holed his putt from 15 feet, and Smith's effort from 12 feet missed on the right.

The venture to extra holes was made possible by Johnson making a mess of the par-3 10th hole. He had a shot bounce down a path into the water, a muddy lie and missed a four-foot putt. It added to a triple bogey, allowing Grace to take the lead.

"Everything I could do wrong, I did wrong on the hole," Johnson said.

"To fight back and birdie 18 two times in a row when I had to, I'm really happy with that."

He was equally happy to see a good result heading into the year's second major. The PGA Championship starts Thursday at Oak Hill.

Until Sunday, Johnson had not finished closer than within five shots of the winner in five LIV Golf events this year. He was never a factor at the Masters. Now he feels as though his game is ready.

"I'm really playing well," Johnson said.

Talor Gooch, coming off two straight LIV Golf victories, played before a home-state crowd in Oklahoma and finished in a tie for 36th.