Here’s 5 groups we’ll be watching at the PGA Championship

As expected at a major that assembles the strongest field in golf, there were plenty of star-filled pairings when the PGA of America released the tee times Friday for the first two rounds of the PGA Championship, which begins Thursday at Quail Hollow in Charlotte.

A trio of big-hitters ... a trio of former PGA Championship winners ... a trio of Rickie, Rory and Rahm. Plus a trio that features the last three majors winners, including Jordan Spieth, angling to become the youngest winner ever of a career Grand Slam. 

Here's a look at the five pairings that popped off the tee sheet:

MORE: Tee times, pairings for PGA Championship first and second rounds

5. Justin Thomas, Patrick Reed, Tommy Fleetwood

Tee time: 8:05 a.m., Hole 10

Reason to watch: In Thomas and Fleetwood, you have two of the hottest players on the PGA and European Tours. And Reed? Well, he's always electric. But there's one thing all three players have in common -- their resumes are all void of a major victory. For Thomas and Fleetwood, a win at Quail Hollow would be the cherry on top of an already spectacular season. And for Reed -- already a career multiple winner on Tour and a Ryder Cup hero -- it would be the next logical step in what has been a stellar early part of his career.

WATCH: Get to know Quail Hollow, host of the 99th PGA Championship

4. Jimmy Walker, Phil Mickelson, Jason Dufner

Tee time: 1:25 p.m., Hole 1

Reason to watch: All three are PGA Champions and it will be an incredibly comfortable pairing for three of the best ball strikers in the game. Walker, the defending PGA Champion, hasn't played his best since that career highlight win a year ago at Baltusrol, but his game looks to be taking a turn for the better. Mickelson and Dufner, meanwhile, are always fan favorites.

MORE: Jimmy Walker getting healthy, looking forward to title defense

3. Jason Day, Dustin Johnson, Henrik Stenson

Tee time: 8:35 a.m., Hole 10

Reason to watch: If you like the long ball, it doesn't get much better than this threesome. All three are also major winners within the last three seasons, with Day taking the 2015 PGA Championship at Whistling Straits, Dustin Johnson the 2016 U.S. Open at Oakmont and Henrik Stenson cashing in at Royal Troon in the 2016 Open Championship. All three players currently reside in the Top 10 of the Official World Golf Ranking, with Johnson leading the way at No. 1. All three have proven to be regular major contenders. Will that continue at Quail Hollow?

2. Rory McIlroy, Rickie Fowler, Jon Rahm

Tee time: 1:35 p.m., Hole 1

Reason to watch: McIlroy is looking for his first major win since the 2014 PGA Championship, with Fowler and Rahm looking for their first major wins, period. Both McIlroy (twice) and Fowler have won at Quail Hollow in the past -- their first victories on the PGA Tour. Rahm has soared to No. 6 in the Official World Golf Ranking. This will be his first appearance in the PGA Championship. Three of the most powerful and flashy players in the same threesome for the first two rounds of the season's final major? Yes, please.

MORE: Why Rory has a prime shot to hoist the Wanamaker again

1. Sergio Garcia, Brooks Koepka, Jordan Spieth

Tee time: 8:25 a.m., Hole 10

Reason to watch: This is the pairing at the PGA Championship that every player in the game wants to be a part of because it features the winners of each of the season's first three majors. It will be extra special for Spieth. Following his Open Championship victory at Royal Birkdale a month ago, the Texan is now just a PGA Championship shy of a career Grand Slam. Should he be victorious at Quail Hollow, Spieth would become the sixth player in history to complete a career Slam and -- having just turned 24 -- also would be the youngest.

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For Garcia, this will be the first major for the Masters champion since becoming a married man, which he did the week after the Open Championship. Now that he's a major winner and things seem perfect in his personal life, will the floodgates open up in the majors? Koepka, the U.S. Open winner, already has six Top10 finishes in majors since 2014. He followed up the win at Erin Hills in June with a respectable T6 at Royal Birkdale last month. Could he snag his first and second major titles in the same year?