Jon Rahm made his first trip to Muirfield Village in a dark suit and a royal blue tie, no golf clubs.

He won the Jack Nicklaus Award as the nation's top college golfer. Rahm graduated from Arizona State in four years, despite speaking little English when he arrived on a campus so big he thought he was in a movie theater when he went to his first class in macroeconomics.

That was four years ago.

Far more meaningful was meeting Nicklaus behind the 18th green after an exquisite performance in the Memorial. Rahm built an eight-shot lead at the turn on the toughest Sunday at Muirfield Village in 42 years. He lost five shots of that lead in five holes. And then he showed equal parts grit and flair by getting up-and-down over the last four holes.

The victory sent him to No 1 in the world.

It felt like a long time coming, even for the 25-year-old Rahm.

He was No 1 in the amateur ranking for a record 60 weeks. Phil Mickelson, whose brother was Rahm's coach at Arizona State, has been predicting greatness since before he won the first of his 10 worldwide titles.

"He just doesn't have a weakness," Mickelson said on Sunday, the same thing he said in 2017 before Rahm won his first event at Torrey Pines with a 60-foot eagle putt on the last hole.

Mickelson also recognized Rahm's passion, so great it can lead to fits of temper and bursts of birdies. There is rarely a dull moment.

"He knows himself," Mickelson said. "He knows that to relax, sometimes he has to let some of his anger out. He can't hold that in. It might upset some people, but he knows that it allows him to be at his best. And so I think that's a big thing, too, is identifying your own self, and he's done a great job of that at a really young age."

Rahm held it together when he was four shots behind on the 13th hole on Saturday. He birdied the next four holes for a 68, which he considered the best round of his career given the wind and the fast, crusty turf. So in a span of 15 holes－six to end the third round, the front nine on Sunday－Rahm went from a four-shot deficit to an eight-shot lead. He is an explosive player, with or without a golf club in hand.

Rahm is the fifth youngest player to reach No 1 in the world, trailing Tiger Woods in 1997, Jordan Spieth in 2015, Rory McIlroy in 2012 and Justin Thomas in 2018. Woods, Spieth and McIlroy had won majors by then, and that's the next step for Rahm.

For now, he is trying to process a lifetime ambition of being No 1 in the world.

He recalled a conversation with his coach when he was in his early teens in Spain. The coach asked what he wanted to achieve.

"I said straight up, 'I want to be the best player in the world.' I made that deal with myself very young," Rahm said. "I started working towards that goal, and everything I've done golf-wise has been to become No 1 in the world and become the best player I can be. It's pretty surreal to think it's happened this quickly. I mean, how many people get to achieve a lifelong dream in their mid-20s?"

McIlroy was 23 when he first reached No 1 in the world at the Honda Classic in 2012, a year after winning his first major, and he recalled the sensation of meeting a goal. The hard part is what comes next.

"It was weird," McIlroy said on Sunday. "Nothing changes. You're still the same. It was hard for me. It was a goal of mine at the start of 2012 and I achieved it pretty quickly. I actually struggled the first couple of months to reassess my goals."

Rahm replacing him at No 1 was not a surprise as much as a mild disappointment. Neither had played particularly well coming out of the three months off from the COVID-19 pandemic. The difference is Rahm won, and it was a big one.

"I'm not saying it's inevitable that Jon was going to be there," McIlroy said. "But he has always had the capabilities."

Rahm surely has all the shots, a remarkable talent who doesn't back down. He also is maturing, not just with his game but his emotions. Rahm has developed a reputation as a hothead－clubs buried into the turf, histrionics after poor shots－that will be difficult to shake. He has tried to tone it down without losing the positive energy that comes with it, and the weekend at Muirfield Village was ripe for anyone to lose it.

He won it with great discipline on the front nine, with that Spanish magic on the back nine. He built a big enough lead that a two-shot penalty assessed after the round－h(huán)is ball moved ever so slightly when he put the wedge behind it before chipping in behind the 16th green－turned a five-shot victory into a three-shot triumph. Rahm didn't see the ball move until shown a close-up on a video screen. He accepted the penalty.

"I wish I could just keep that birdie because it was one of the greatest shots of my life, right?" he said.

So one of his greatest shots turned out to be a bogey. He can live with that.