Rory McIlroy arrived at Chambers Bay certain in his position as the No 1 player in the game and determined to prove it.
ut even after carding a final-round 66 to finish tied ninth on that US Open staple of even par, the 26-year-old woke up yesterday realising that may only be half true. Or possibly not true at all.
Sure, he's top of the world rankings but US Open winner Jordan Spieth - arguably the poor relation to McIlroy in every physical aspect of the game bar putting - has now won the last two Majors and more world ranking points than anyone else this year.
Between them, McIlroy and Spieth have won the last four Majors, with the 21-year old American, the youngest US Open winner since Bobby Jones in 1923, now chasing his place in the history books.
It will be sobering for McIlroy to realise that Spieth (right) is now the youngest player to win the Masters and the US Open, beating the two greatest players of all time.
Jack Nicklaus was 23 and Tiger Woods 24 when they completed the double. But that's not all.
Spieth is also on track to complete the single season Grand Slam and with just a month to go before the game's elite gathers at the Home of Golf for The Open on the Old Course, McIlroy has some serious questions to answer.
The man who's arguably his No 1 fan, 2014 European Ryder Cup skipper Paul McGinley, spoke before the Masters of McIlroy as head and shoulders above everybody else in the game.
By Sunday night McGinley was admitting that McIlroy's reign is now under threat and while he believes Spieth's majestic rise to the top will only be good for the Holywood man, it remains to be seen how he reacts.
"When someone wins their first Major like Jordan did at the Masters, you expect added pressure and expectation put on their shoulders, but he just went and won the next one! He's got something special," McGinley said.
"Rory has now got to step up to the plate. As commendable as his performance was (on Sunday) and during the final round of the Masters, the bottom line is he's had too much ground to make up in both tournaments.
"He's made the mistake of getting off to slow starts in each of the last two Majors and Jordan has gone on to win both of them. He's putting it up to Rory, which can only be a good thing."
McIlroy was asked about LeBron James' assertion before a decisive game in last week's NBA play-offs that he was the No 1 player in the sport - whether that claim was super confidence or arrogance or a psychological ploy.
"I think when LeBron talks about that, that's not confidence, that's a fact," McIlroy said. "I guess, when you look at how he's carried his team in these finals. . . So if you look at the numbers, you can really see he is the best player in the world.
"And I guess for me I feel the same way, when I look at the World Rankings and I see my name up at the top. If you look back at the last four or five years, I guess I've won more Majors than anyone else in that time period.
So do I feel like the best player in the world? Yes. And obviously I want to go out every week and try to back that up and show that."
LeBron - another Nike god - didn't win the game with the Cleveland Cavaliers as Steve Curry led the Golden State Warriors to a 4-2 win in the best-of-seven series.
Curry is a more cerebral player than James, and a better team man. There are clear comparisons with golf's new big rivals.
"Jordan and Rory are very difficult to compare because they are so different," Graeme McDowell said after Spieth's stunning Masters win. "I think it's a good thing to see a guy coming through who is not Dustin or Rory, guys like that who are dominating with physicality.
"We see a guy coming around who is average build, average size, hits it average distance. He's not short but he's not the longest player on the planet and he gets it done other ways. That's exciting."
Their rivalry is now very much the story line in the game - Spieth as the Djokovic to McIlroy's Roger Federer or Rafael Nadal.
The US media has certainly been crying out for a figure to replace Woods as the face of golf, and what McIlroy lacks as a European, clean-cut Texan Spieth gives them red, white and blue.
In a 5,000-word transcript of his US Open media conference on Sunday night, there was not one mention or question about McIlroy.
Indeed, it's McIlroy who should be asking himself questions, not just about his putting, which remains streaky and frequently suspect when compared to an artist like Spieth, but also about the way he mentally goes about breaking down a golf course.
Before Spieth spoke of his delight at winning without his "best stuff", McIlroy admitted: "I've got a couple of weeks to work on my putting and get that up to the shape that it has been in and especially the way it was last year. If I can do that, keep the long game where it is, I'm really excited about what can happen over the summer."
Spieth's dynamic interaction with his caddie, Michael Greller, clearly audible on the final day, was one of the highlights of the television coverage. But can McIlroy honestly say he was as well prepared?
Greg Norman wasn't the only one to notice Spieth's unworldly maturity for a 21-year old.
"He is light years ahead of everybody else on tour because he has a complete game," Norman said of the greatest brain in the game since Nicklaus.
"He has composure and he is mature beyond his years. Some of the decisions he has made out here, he has really made collective positive decisions.
"Maybe it's his dad, maybe it's his caddie, maybe it's his coach, I don't know, but he has made some phenomenally mature decisions out there and never really lets things get away from him.
"On the front nine (on Sunday) he was a little bit edgy, a little bit agitated, a little bit out of sync, the putting stroke was a little bit quick.
"But as he got into it and he got into a position of winning, everything settled in."
Chubby Chandler once damned McIlroy caddie JP Fitzgerald with faint praise, saying: "He may not be the best caddie in the world, but he's the best caddie for Rory."
That may still be true but if McIlroy is to outfox Spieth at St Andrews, a course he admittedly dominates like nobody else, he's going to need every aspect of his game on song and a game-plan that's foolproof.
He may also have to deal with an old Irish amateur team-mate in Shane Lowry, the other shining light from what was a dark Sunday for Dustin Johnson, whose closing three-putt may haunt him for years.
Lowry's final-round performance was massively encouraging for the mortals of the world, not to mention uplifting as he played dressed from head to toe in black as a mark of respect for the victims of the Berkeley tragedy.
While the achievements of McIlroy and Spieth look beyond most ordinary players, Lowry's devastation at finishing five shots off the pace in a share of ninth with his former stablemate can only be viewed as a positive.
Not only did he move up five places to 45th in the world and secured Special Temporary Membership of the PGA Tour thanks to a cheque for €210,476, the 28-year-old Offaly man showed how far he's come since last year's Open championship at Royal Liverpool.
He was tied for ninth there too but the shift in expectations is clear.
While he backed into a top-10 finish at Hoylake, Lowry had a legitimate shot at victory on Sunday night, having started the day just three strokes off the lead.
He simply fell victim to a cold putter but his total of level-par 280 would have been enough to win six of the last nine US Opens, and while he was suitably downcast at the finish, it's a week that can only make him stronger.
"I feel like I played the golf to really have a chance to win at the end," Lowry said after six at the last and a one-over 71. "I missed a couple of short putts for par that you can't be doing on days like this.
"I just didn't do enough. Had I holed a few more putts, I would have had a chance coming in on the last few.
"You hope to learn from things like the last round. I thoroughly enjoyed my week. Loved the golf course, I loved how tough it played. Tends to suit me a lot, tough golf courses.
"Overall I'm pretty pleased at how I played. When you walk away from a Major championship and you feel like you played the golf to win you've got to be happy with yourself.
"I left myself a couple of putts that were really tough downhillers. It was such a grind out there. It was quite tough.
"And I felt like we were playing catch-up on the group in front of us all day, as well."
Lowry was referring to Andres Romero and Brandt Snedeker but he could easily have been talking about the pair behind him and JB Holmes - 21-year old Australian Cameron Smith, who eagled the last for a 68 to tie for fourth, and 2010 Open champion Louis Oosthuizen, whose six-under figures for the last seven holes gave him a 67 and a share of second with the unfortunate Johnson.