By Shelby Harrison

The golf season began with a hierarchy that seemed clear:

Rory McIlroy, Jordan Spieth and Jason Day and some of their competitors.

This became the year of the first-time major winner, none more improbable than the 37-year-old Texan who walked off with the Wanamaker Trophy last night.

Jimmy Walker sank a 3-foot par putt on the 18th green at Baltusrol to win the PGA Championship by one stroke over Day, the defending champion. He finished at 14 under par for the tournament, which he led after every round.

It took 36 holes on yesterday after rain Saturday delayed the start of his third round. And it took a tension-filled final hole, which Day finished with an eagle just as Walker was coming up the fairway. But when Walker got out of the greenside rough safely and two-putted from 33 feet, golf’s year of the upstart champion was complete.

Danny Willett won the Masters, Dustin Johnson won the U.S. Open and Henrik Stenson won the British Open to make this the first year since 2011 that first-time major winners claimed all four majors. It was only the third such year since 1969.

“It just shows how deep golf is,” Walker said. “Anybody can win.”

Neither of the other three major champions this year were ranked lower than 12th in the world when they won. Walker entered this week with far less stature, ranked 48th and coming off missed cuts at the past two majors.

He won five PGA Tour events between 2013 and 2015, but spent less time in front of cameras than he did behind one. In his spare time, Walker attaches his camera to a telescope and takes photos of stars in the nighttime sky, many of which are listed for sale online at $21.44 each. Now, he can add to that an astronomical prize: a $1.8 million check from the PGA of America.

“I feel like I can do it,” Walker said. “I can do it now. I can win a major championship. It’s unreal, it really is.”

In a tournament that saw McIlroy miss the cut and Spieth fade from contention, Day stayed close to Walker throughout the weekend. Henrik Stenson, who won the British Open only two weeks earlier, also pulled within one stroke of the lead at one point late Sunday afternoon. But Stenson stumbled on the back nine to finish tied for seventh. And Day, the world No. 1, was done in by two bogeys on the first three holes and some narrowly missed birdie putts.

Mere seconds after Day reached the 18th green in two shots, he saw on the scoreboard that Walker had just birdied the 17th hole to go ahead by three strokes. Day threw his putter and slumped his shoulders. Barring a final-hole meltdown by Walker, the tournament was over.

“Hats off,” Day said, “because I mean, it’s not easy to win tournaments, and he controlled himself pretty darn well all day.” Since both players are among a handful who sleep in their own motor homes at tournaments, they see each other often away from the course. “He’s a tremendous bloke,” Day said.

The final round was played under an extraordinary rules provision invoked by the PGA of America. With the course soaked and more wet weather in the forecast, players were permitted to play preferred lies. Known as “lift, clean and place,” this meant players could lift their ball off the fairway to remove mud and choose a preferable spot to play from, provided that spot was within one club length of the original lie.

The rule is typically invoked amid wet conditions on the PGA Tour, but Sunday marked the first time it had been used at any of the three American major championships, according to PGA of America historian Bob Denney. In a statement, the PGA of America said the decision was made in the hope of completing play Sunday.

To that end, the PGA also didn’t re-pair players after the third round, which prevented Day and Walker from going at each other in the flesh.

“It would have been nice to be able to play in the last group with him, just to be able to go back and forth with him, maybe put a little bit more pressure on,” Day said. “More mistakes or crucial moments can happen in situations like that.”

In the absence of that kind of tension, Walker played a mistake-free final round. He went without a bogey in his last 28 holes of the tournament. And even when Day’s eagle on the last hole made for a stressful walk up the 18th fairway, Walker was undaunted.

“Incredible finish, it really was,” Walker said. “It just puts a smile on my face. It hasn’t even sunk in yet.”