5 storylines heading into the 99th PGA Championship

The PGA Championship might be considered the forgotten major of the four, but there's plenty on the line this week at Quail Hollow Club.

Here's five storylines heading into the final major championship of 2017:

Jordan Spieth chases history

With a win this week in Charlotte, the 24-year-old Spieth would not only join Jack Nicklaus, Tiger Woods, Gene Sarazen, Gary Player, and Ben Hogan as the only players to achieve the career grand slam - he would also become the youngest.

"One more player sits at the doorstep of joining our little club," Nicklaus said in a Golf Channel video. "Good luck young man."

Woods was also 24 when he completed the feat at St. Andrews in 2000, but the Texan can eclipse Tiger by six months this week.

"Do I have to be the youngest? No, I don’t feel that kind of pressure," Spieth said on Wednesday. "Would it be really cool? Absolutely"

Rory McIlroy returns to familiar place

It's been an interesting season for McIlroy - with a new equipment deal, a new marriage, and a new caddie - but there are no wins to his name. The Northern Irishman was unbelievable off the tee at Firestone, and now comes to a course where he's been very successful. McIlroy owns the course record (61) and has a pair of wins at Quail Hollow, and he'll next try to salvage his season in Charlotte with a sixth career major title.

Can Dustin Johnson regain his form?

The world No. 1 came into the season's first major at Augusta as the hottest man in golf after picking up three PGA Tour victories early in the year. However, Johnson suffered a freak accident on the eve of the Masters and was forced to withdraw just minutes before his Day 1 tee time. The 33-year-old has been unable to regain his game since then, but will try end his drought with a second career major title.

How will Quail Hollow play?

The site of the Wells Fargo Championship has undergone significant changes since May 2016. The course switched its greens from rye to Bermuda grass, eliminated thousands of trees, and changed four holes.

"The first is a drastic change, obviously," McIlroy said at his Tuesday press conference. "The fourth and the fifth holes are a little different, but it used to be, you got through the first five holes in 1- or 2-under par, and that was a decent start. Now it's you get through the first five holes in even par, and that's when the golf course starts to open up for you."

Phil Mickelson looks to help Presidents Cup chance

The United States Presidents Cup team won't be picked until early September, but it's crunch time for Phil Mickelson. The 47-year-old, who hasn't won on tour since the 2013 Open, has played in every U.S. team event since 1993, but sits in 17th place in the American standings.

"I want to make that team,” Mickelson told Will Gray of the Golf Channel. "It’s more than a streak as much as it is I just love those events. I love those weeks, I love the time with the guys and I just really cherish those memories."

Mickelson trails 10th-ranked Kevin Chappell by 882 points to gain the final automatic spot on the team.

(Photos courtesy: Action Images)