Morikawa narrowly avoided another play-off heartbreak after Justin Thomas squandered a three-shot lead with three holes to play at Muirfield Golf Club in Ohio.

The 23-year-old Morikawa, who suffered a play-off loss at the Charles Schwab Challenge last month to Daniel Berger, hung on after Thomas bogied the 16th and 18th in regulation to send the pair to extra holes.

Tied at 19-under par after four rounds, the duo put on a putting masterclass on the first play-off hole for birdies with Thomas letting out a roar after sinking a 50-footer.

Morikawa had to make a 25-foot putt to keep playing and he duly obliged.

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Thomas, the 2017 US PGA Championship winner who had been flawless through the first three rounds, missed the fairway on the third play-off hole and got stuck behind a tree, and it was Morikawa who kept his nerve for the win.

Morikawa will rise to No.13 in the world – one spot ahead of Tiger Woods – and said it was a huge stepping stone.

"We got No.1 (victory) out of the way. We got No.2. Let the gates just open and let's keep going," the American said.

“Those three holes were a grind, obviously Justin making that birdie putt on that first playoff hole, I had to make it, or else we go home again.” – Collin Morikawa

But it was a bitter loss for Thomas, who had a two-stroke lead over Norwegian Viktor Hovland going into Sunday.

With three holes to play, he was three shots ahead of Morikawa, who made only one birdie which was enough for a six-under 66 to force a playoff.

"It's completely unacceptable to give up a three-shot lead with three to go," Thomas said.

"I'm upset, I'm disappointed in myself."

After missing the cut in three of his previous four events since the Tour's resumption from the coronavirus-forced shutdown, Day was the best-placed Australian in a tie for seventh at 11 under.

Countryman Matt Jones (70) finished 14th, one stroke further back.

Day's closing five-under-par 67 on his home course in Ohio – where he plays with Jack Nicklaus – was also the former World No.1's equal-lowest round since his fourth-place finish at the Pebble Beach Pro-Am five months ago.

After slumping to 63rd in the rankings, Day's strong showing propelled the 31-year-old from 101st to 79th in the FedExCup standings.

He gets another chance on his home course in this week's Memorial Challenge.

The Workday Charity Open at Muirfield Village was added to the PGA Tour's calendar after the John Deere Classic, which was to be held in Illinois, was cancelled due to the COVID-19 pandemic.