Morikawa ended the drama-filled day at Muirfield Village Golf Club with a mundane two-putt par to capture his second career PGA Tour title. But it was a thrilling set of events that led the 23-year-old into extra holes against world No. 5 Thomas.
After play was moved to the morning with inclement weather expected around Dublin, Ohio, in the afternoon, Thomas entered the final round with a three-shot lead. But it quickly vanished on the heels of two early bogeys and a 4-under start by Morikawa through the opening five holes.
Down three with 11 holes remaining, Thomas found another gear. He played the next eight holes at 7-under par, capping the run with an emphatic eagle on No. 15 to hold a three-shot lead on the 16th tee.
Morikawa's chances appeared to have vanished, but a costly bogey from Thomas on the par-3 16th kept the door open.
After he birdied the 17th hole to get within one, Morikawa made par on No. 18 to post a 6-under 66. Thomas, meanwhile, failed to save par after his drive found the fairway bunker. He then missed an 11-footer for the victory, squandering his lead.
"It's completely unacceptable to give up a three-shot lead with three to go, Thomas said after the loss, according to Golf Channel's Ryan Lavner. "I'm upset. I'm disappointed in myself."
Fireworks flew during the first playoff hole - No. 18 at Muirfield. Thomas drilled an unlikely birdie putt from over 50 feet, but Morikawa answered by sinking a 25-foot effort to force another hole.
After both made par on the second extra hole, the playoff shifted to No. 10.
Thomas' drive sailed right and ended up directly behind a narrow tree in the rough. Morikawa split the fairway and proceeded to hit another flawless approach shot to nine feet.
Thomas failed to save par, allowing Morikawa to two-putt for the victory in his second playoff since the PGA Tour returned in June. Morikawa lost to Daniel Berger on the first extra hole at the Charles Schwab Challenge.
"Two playoffs now, and finally got one done," Morikawa said after the win. "But Justin is an awesome player. He was one of the first people that kind of helped me when I turned pro last year in Canada, so I owe a lot to him. I'm super happy I closed it out after those first two days."
Morikawa, who held a three-shot lead after 36 holes, now has more PGA Tour victories than missed cuts in his career. Tiger Woods is the only other golfer who can lay claim to that feat.
Here's how the top of the leaderboard finished:
|Place||Player||To Par||R4 Score|
*Denotes playoff victory
Viktor Hovland hung around early in the day. He held the outright lead after three birdies through his first five holes, but he played 2-over from that point on to finish alone in third.
The PGA Tour remains at Muirfield Village for next week's Memorial Tournament hosted by Jack Nicklaus.