When Rory McIlroy won The Open for the first time in his career just over three-years ago, he was the king in waiting.
After beating Rickie Fowler and Sergio Garcia by two strokes, McIlroy won his third major, having previously been victorious at the US Open and USPGA Championship.
Three-quarters of the way to a career Grand Slam, he spoke about playing at The Masters the following year, looking to make history.
To sit here 25 years of age and win my third Major Championship and be three-quarters of the way to the career Grand Slam, yeah, I never dreamed of being at this point in my career so quickly.
Even though there's still one major left this year that I want to desperately try and win, I'm looking forward to next April and trying to complete the career Grand Slam.
All eyes were focused on McIlroy going into the 2015 Masters, but it would be won by Jordan Spieth. His maiden major title would quickly be followed by a US Open win, two months later. With a potential calendar-year Grand Slam on the line, Spieth finished one-shot short of making a play-off at The Open at St Andrews and finished second at the USPGA to complete a historic year.
Since the 2015 US Open, Spieth could not get his hands on another major title, until last month. Just under three weeks ago, he played his way around Royal Birkdale (including an unplanned trip to the driving range) to win the title by three strokes.
The one that won it. #TheOpen pic.twitter.com/RfrJdByJXP
— The Open (@TheOpen) July 23, 2017
Along with Jack Nicklaus, Spieth is now the only other player to win three separate majors before his 24th birthday. He hit that milestone four days after his Birkdale triumph. McIlroy was 25, when he won at Royal Liverpool in 2014.
This week, the USPGA Championship takes place at Quail Hollow, with Spieth looking to complete the career Grand Slam before McIlroy, despite the Irish golfer's two-and-a-half year headstart.
Speaking ahead of the tournament, Spieth admitted that the expectations of becoming the youngest player to complete the Grand Slam were not weighing on him.
Expectations, I really don't feel any. This whole, this is a chance to complete the career Grand Slam; I'm here, so I'm going to go ahead and try. But I believe I'm going to have plenty of chances, and I'm young enough to believe in my abilities that it will happen at some point.
Do I have to be the youngest? No, I don't feel that kind of pressure. Would it be really cool? Absolutely. And I don't come to a tournament unless I plan on giving it my all in preparation to have a chance and to ultimately close a tournament out.
McIlroy has won at the North Carolina venue on two occasions and holds the course record of 61, but there will be nothing he can do it Spieth is victorious on Sunday evening.
In his four previous USPGA Championships, the Texan missed two cuts, finished second in 2015 and was a tie for thirteenth last year. It now becomes the most important tournament of his year.
Since the 2015 Masters, McIlroy has had three top-ten finishes at Augusta in his bid to win The Masters, but has never been in contention to win the Green Jacket.
In the storied history of the game, only five players have won all four of the modern-day majors and Spieth could easily beat McIlroy to become the sixth.
13 players in total are missing one major to complete the Grand Slam. In the next three majors, three players can theoretically complete the feat. Spieth (USPGA Championship), McIlroy (The Masters) and Phil Mickelson (US Open) could all join the club of Gene Sarazen, Ben Hogan, Jack Nicklaus, Gary Player and Tiger Woods.
Spieth's Open triumph has added a level of pressure to both himself and McIlroy. Both players can hand the opportunity to their each other, if they don't win that elusive major.
The race for the Grand Slam will make the upcoming majors turn into riveting viewing.
