SPRINGFIELD, N.J. — A stale year for Jimmy Walker came to life Thursday in the PGA Championship when he saw putts drop and wound up leading a major for the first time in his career.

A great year might get even better for Henrik Stenson.

Walker took advantage of smoother greens in the morning Thursday at Baltusrol by rolling in six birdies for a 5-under 65, giving him a one-shot lead after the opening round of the final major that delivered its share of surprises.

U.S. Open champion Dustin Johnson, with a chance to go to No. 1 in the world, was in the trees, in the water and couldn’t get out of a bunker. He managed only one birdie in a round of 77 that wasn’t enough to beat 15 of the club pros at Baltusrol.

He wasn’t alone in his misery. Rory McIlroy took 35 putts and didn’t make a single birdie in his round of 74 that left him so frustrated that he returned to Baltusrol late in the day with his putter.

Stenson had his struggles on the greens, too, but he was rolling right along at the end with three birdies over his last seven holes for a 67, leaving him only two shots out of the lead as he tries to become the first player since Ben Hogan in 1953 to win back-to-back majors at age 40.

“It’s going to be a great season for me,” Stenson said. “But at the same time, I want to give myself a chance to try to make it the best season.”

Walker’s year has been so mediocre that he has finished within five shots of the winner only once this year, at Torrey Pines. He is on the verge of falling out of the top 50 in the world ranking and hasn’t given as much thought to Ryder Cup with qualifying a month away from ending.

“I’m a good putter,” Walker said. “Like good shooters, just keep shooting. I’m just going to keep putting, and they’re going to start going in.”

And they did.

Walker wound up with a one-shot lead over two-time major champion Martin Kaymer, Emiliano Grillo and Ross Fisher. Kaymer had the best score in the afternoon, when the blend of poa annua and bent grass on the Baltusrol greens became a little more difficult to navigate.

“I feel like all year it’s just been real stale and stagnant,” Walker said. “It’s just ebbs and flows of golf. Just haven’t been scoring. … It’s frustrating. I would have loved to have had a better year than I’ve had so far to this point, but I know there’s always time to play well at the end of the year.”

Even with afternoon gusts that approached 20 mph, and the late threat of rain, Baltusrol still allowed for good scoring.

Twenty players were at 68 or better, a list that included defending champion Jason Day.

Jordan Spieth only regrets one hole, the par-4 seventh, when he lost his ball so far to the right he had to chip back into thick rough and wound up three-putting for a double bogey. That was his lone mistake. He rolled in big putts on the 15th for par, 16th for birdie and closed with a two-putt birdie to get back to even-par 70.

Day played in the morning group with McIlroy and Phil Mickelson, and he was the only player without much stress. Mickelson, just 11 days after that magnificent duel with Stenson at Royal Troon, was 4 over through 11 holes when he rallied with a trio of birdies late in his round to salvage a 71.

“It’s not the start I wanted. It’s not indicative of how I’m playing,” he said. “But I’m back to where tomorrow, if I play the way I’ve been playing, I should be OK.”

Grillo had a chance to at least join Walker in the lead when he was at 4 under with the final two holes par 5s. He made par on both. Fisher made birdie on the two closing par 5s for his 66. Kaymer started his afternoon round on the back nine and kept it together with two pars, including a 35-yard bunker shot on No. 8 to within 3 feet.

“There’s nothing easy on the golf course today,” Kaymer said. “I just didn’t miss many fairways and therefore, you can create some birdie chances. But at the end of the day you still need to make the putts.”

Walker kept the ball in play off the tee until late in his round, and he was particularly sharp with his scrambling out by getting up-and-down six times.

Johnson, meanwhile, was all over the place.

Dressed in black and clean-shaven, he took a double bogey from the trees and by missing a short putt on No. 3. He added three more bogeys with wild drives. He drilled a bunker shot into the lip on No. 11 for a double bogey. And he ended his round by chopping up the par-5 18th, the easiest at Baltusrol, for a bogey.