FARMINGDALE, N.Y. — The PGA Championship begins Thursday, and that means Jordan Spieth will attempt for the third time to complete the career Grand Slam and join an elite group made up of the most iconic names in the history of golf.

However, the game hasn’t been too kind lately to Spieth since his last victory. That came in the 2017 British Open at Royal Birkdale, where he joined Jack Nicklaus as the only two men to win three legs of the Grand Slam before age 24.

Spieth, 25, enters the opening round at Bethpage Black without a top-20 finish on the PGA Tour in 13 tournaments this season, dropping him to 150th in the FedExCup point standings. The No. 1-ranked player in the world for 26 weeks in 2015 and 2016 has seen his ranking slip to No. 39. He has just one top-10 finish in his last 26 tour events.

Speaking Wednesday at his pre-tournament news conference, Spieth said that his issue is with the driver, that his swing had gotten too upright. It’s taken some time to remedy that fault, but he thinks he is making progress.

“My setup got a little bit lazy, and, instead of finding that out, my swing started to kind of go up instead of around me,” he said. “I’m trying to get it right back to where it was in 2017, where I was first in tee to green on the tour, and we have all the data points to do it. It’s just a difficult move for me right now, and it just takes a little bit of time to work it back and get the timing right.”

He showed some improvement last week at the Byron Nelson Classic in his hometown of Dallas, shooting 68, 67 and 67 in his first three rounds before closing with a 71 that dropped him into a tie for 29th. He said he felt so good with the driver that he tried to bring a big draw back to his array of shots, a mistake.

“I hooked a couple out of play … making kind of a dumb decision to start the round to try to bring in a couple more shots but not going about it the right way,” he said.

Spieth still can make history this week as the sixth player to complete the Grand Slam, joining Gene Sarazen, Ben Hogan, Nicklaus, Gary Player, and Tiger Woods. He’d be the second youngest (25 years, 9 months, 22 days) to achieve the feat, trailing only Woods (24, 6, 23).

“It would be a pretty unique fraternity to be in there,” he said. “That would be a dream come true for me. But I also recognize that if I continue to stay healthy and play well, I’ll have, I don’t know, 30 chances at it. One of them is bound to go my way, right?

“I just go week to week and try and set up to hit my first tee shot [Thursday] down the fairway and then try to hit the second shot on the green and then make a putt and figure out how to birdie the next. It’s going to be very here in the moment for me, just as it is at every major. I feel like I’m more patient in majors, with letting courses come to me, than I am at other tournaments, and I feel like this is a good time for me to test that out.“

Spieth and 155 other contestants will test the big and brassy jewel of the five courses at Bethpage State Park. The Black course will play to par-70 and measure 7,459 yards, which will play longer because of recent rains that softened the course.

Three par-4 holes are more than 500 yards, and three others are in the 478- to 490-yard range. Most players have praised the condition of the greens, which, for the most part, are flatter than what you might see on a major championship layout.

For Spieth, who used the word “was” rather than “is” to describe his slump, it’s a matter of staying positive and getting himself in the hunt.

“It’s just one of those things where you’ve just got to block out the noise and stay the course and believe in yourself,” he said.