David Lingmerth is the winner of the 40th Memorial Tournament.

David Lingmerth is the winner of the 40th Memorial Tournament.

Who?

"Can't believe it right now. I'm so happy," Lingmerth said.

Neither can we.

Entering last week, Lingmerth, a 27-year-old native of Sweden, was the 212th-ranked golfer in the world. He shot a four-day total of 15-under-par 273 and defeated Justin Rose in the third playoff hole June 7 at Muirfield Village Golf Club.

Lingmerth is now ranked 71st.

"I guess I didn't really think about (winning at the start of last week) that much," he said. "I just tried to put a few nice rounds of golf together, and that was pretty much it."

Lingmerth opened the tournament June 4 with a 67 and carded a 65 in the second round to place himself in contention on the weekend. He had been in contention on the PGA Tour before, having had runner-up finishes at both the Humana Challenge and The Players during his rookie year in 2013.

But in the third round of the Memorial, Lingmerth shot even-par 72 to fall three strokes behind Rose and two behind Francesco Molinari. In the final round, Lingmerth was three strokes better than Rose to force a playoff while a double bogey at the par-3 16th ended Molinari's chances. It was the second consecutive playoff at the Memorial after the tournament didn't have one from 1992-2013.

Both players carded pars on No. 18 twice to force the third playoff hole to move to No. 10 -- making it the longest playoff in Memorial history. Lingmerth's tee shot on the 471-yard, par 4 found the fairway while Rose was in the right rough behind a tree.

"I should've hit a 3-wood," said Rose, who is a seven-time winner on the PGA Tour, including the 2010 Memorial and the 2013 U.S. Open. "I hit my drive behind that tree in regulation, so to do it again in the playoff -- I will rue that mental decision."

Lingmerth was away and put his approach in the center of the green. Rose had 147 yards to the hole, but the tree forced him to hit a low cut. His ball found the rough on the left side of the green, and he was unable to get up and down for par. Lingmerth made a 4-foot, 6-inch putt for the victory.

"I don't know (Lingmerth) really at all, just saying 'hey' in passing," Rose said. "He seems cool, calm and collected. He did a good job. He kept it together well and he finished off some nice putts."

Before the playoff, Masters champion Jordan Spieth provided the Sunday drama with a final-round 65. When the 21-year-old finished, he was two strokes behind leaders Lingmerth, Rose and Molinari, who were just making the turn.

"That was one of the better rounds I've played in a long time," Spieth said. "It's not playing easy out there. I thought that if I played great golf I'd shoot 5-under today, so to grab a couple extra is nice."

Defending champion Hideki Matsuyama and 2002 champion Jim Furyk tied for fifth at 12-under. Five-time winner Tiger Woods finished in last place thanks to a third-round 85. It was his worst score as a pro, topping an 82 he shot in the second round of the Waste Management Phoenix Open on Jan. 30.

"This is a lonely sport," Woods said. "The manager is not going to come in and bring the righty or lefty. You've just got to play through it. It's one of the hardest things about the game of golf and one of the best things about the game of golf."

Big names aside, it was the relative unknown Lingmerth who came out on top. And to the winner go the spoils.

"Let's go have a milkshake," Lingmerth said at the conclusion of his post-tournament press conference, referring to the iconic Muirfield Village treat.

"He said he's avoided the milkshakes all week," Jack Nicklaus said. "Now he can have one."

"It's time," Lingmerth said.