By the time he walked to the first playoff tee, he was ready.
Lee earned his first PGA Tour victory when he parred the second hole of Sunday's sudden-death playoff, eliminating David Hearn after Kevin Kisner and Robert Streb faltered on the first playoff hole.
"All I can say is wow," Lee said. "I finally did it."
Lee, Hearn, Kisner and Streb were tied at 13 under after four rounds on the Old White TPC course. And Lee wasn't in a good place mentally heading into the playoff.
"I was so nervous," he said. "My head was blank, and I was just trying to breathe."
For good measure, Lee said his caddie, Kurt Kowaluk, put the piece of paper indicating his playoff starting position into a mock wishing well on the par-3 18th tee.
"He put it in there so I can win it," Lee said.
By then, Lee had his focus back.
"I felt ready," he said. "I felt like I could really win this thing."
The South Korean-born New Zealander earned $1.2 million and became the ninth first-time winner on the tour this season.
The former U.S. Amateur champion was competing in his 27th event this season, including his eighth in nine weeks. He is trying to qualify for the international team for the Presidents Cup in October in South Korea. He was 47th in the standings heading into The Greenbrier Classic.
"I never get tired of playing golf," Lee said. "I mean, it's my job, and I just love doing it, and I'm just happy to be out here every week."
Kisner shot a 6-under 64 to get to the clubhouse at 13 under.
Hearn (67) and Lee (67) birdied No. 17 to join the playoff. Both missed birdie putts for the lead on the final hole in regulation.
Streb shot a 5-under 65 in the final round by making five birdie putts on the back nine with a 56-degree wedge after breaking his putter on the ninth hole. The putter broke when Streb tossed it at his bag next to the green.
"It hit the bottom of the bag and the (putter) head went flying," Streb said. "It was not my intent, but that was what happened. And so I said, well, let's see what we can do with a wedge."
He three-putted No. 17 for bogey, but got in the playoff with a 6-foot birdie at No. 18.
Streb was allowed a replacement putter for the playoff, but he never got to use it after missing the green.
Lee and Hearn made birdie putts on the first playoff hole, also eliminating Kisner, who lost in a playoff for the third time this season.
On the second playoff hole, Hearn drove behind a tree on the par-5 17th and made bogey.
"That was probably the only bad tee shot I hit all day," said Hearn, who is still looking for his first PGA Tour win in 164 events. "I've just got to keep giving myself chances like this, and it's going to happen soon."
Lee also missed the fairway, but reached the green in three shots and two-putted from across the green for par.
It marked the third playoff in the tournament's six-year history.
Tiger Woods started the day seven shots behind the leaders, shot a bogey-free 67 and said he made some "nice strides" heading into next week's Open Championship.
"Best I've hit it in a long, long, long time," Woods said. "I had full control over all clubs. This could have been one of those special rounds."
Woods broke a streak of 55 consecutive rounds with at least one bogey. It was his first time under par in a final round since the 2013 Tour Championship.
Lee, Hearn, James Hahn and Greg Owen earned spots at St. Andrews. There also were four spots handed out a week ago at the Travelers Championship and one more is available this week at the John Deere Classic.
Russell Henley shot 63 and finished fifth at 12 under. Seven others were at 11 under, including Chad Collins (69), who was tied for the lead before bogeying the final two holes.
Lee wins 4-man playoff for 1st PGA Tour victory
Danny Lee wins a four-man playoff to win the Greenbrier Classic on Sunday for his first PGA Tour victory.