Until now, the one thing stopping the Spaniard from becoming a major winner was himself, having too often overheated when a calm head was needed in his quest to follow in the footsteps of Seve Ballesteros, Jose Maria Olazabal and Sergio Garcia.
Even on this occasion, there were signs that the 26-year-old was starting to get a bit rattled in Friday’s second round until a holed bunker shot proved a timely tonic as Rahm eventually went on to become the first Spanish player to be crowned as US Open champion.
Just 10 weeks old, Kepa, his son, was oblivious to what had just happened as Rahm cradled him in his arms as he walked off the 18th green with wife Kelley, but, without him coming into the world, this momentous occasion in his career may not have happened.
“In the past, I've gotten frustrated in the US Open,” admitted Rahm as he celebrated a success that delivered an added bonus as he jumped above both Dustin Johnson and Justin Thomas to become the world No 1 for a second time.
“I've made a lot of birdies and a ton of bogeys and double bogeys, and I was able to kind of switch it up this week and actually made more birdies than bogeys and get it done.
“I believe it's because I really set out to be an example for my son that he would be proud of, and I've done some stuff in the past on the golf course that I'm not proud of, and I wish I could eliminate it.
“I believe becoming a dad was always going to help me because before, I could always have the excuse that getting mad helped me out, helped me win golf tournaments, but right now I'm a role model to my son. I'm going to be, as I am to many kids out there.
“Now I understand what I can do, and I know I can perform at my best without showing my frustration so much. I made that deal with myself after the third round of the PGA (at Kiawah Island in May). I wasn't happy with how I ended, and I could have handled it better, and I vowed to myself to be a better role model for my son.
“He won't remember any of this because he's only ten weeks old, but I do. Hopefully in the future, he can grow up to be someone who's proud of his dad. I hope I can provide that example.”
Golf in general should feel proud of Rahm at this moment in time, having shown a real touch of class in the way he handled the bitter disappointment of being turfed out of the Memorial Tournament in his previous start when holding a six-shot lead after testing positive for Covid-19.
There was no bitterness or animosity whatsoever about that, taking it firmly on the chin and not pointing fingers of blame at anyone. After his six-under-par 278 total proved good enough to get the job done, Rahm talked about “believing in karma” and he later revealed how two European legends had helped convince him that the smile would soon be back on his face as he spent time in isolation.
“The first person who called me when I was in the isolation trailer was Padraig Harrington,” said Rahm of Europe’s current Ryder Cup captain and a three-time major winner.
“He told me a story in which he was leading by five after 54 holes (in the 2000 Benson & Hedges International Open at The Belfry), signed the wrong scorecard, and got disqualified. He said he got a lot more from that instance, he learned a lot more than he would ever learn from the win.
“Nick Faldo texted me the next morning and told me a story of how he was winning a tournament. He was leading by six with six holes to go and got disqualified, as well, and how he learned from that and got a win the week after, I think it was the Million Dollar Shootout in South Africa.
“I believe from the biggest setbacks we can get some of the biggest breakthroughs, and that's why I stay so positive. That's why I kept telling Kelley, when she was devastated about what happened and my family and everybody around me, something good is going to come.
“I don't know what, but something good is going to come, and I felt it today out there on the golf course and I knew today was my day.”
Having become close friends, partly through Tim Mickelson having been his college coach at Arizona State, Rahm was one of the first to congratulate Phil Mickelson after he became the game’s oldest winner in the US PGA Championship.
In a reciprocal gesture, Mickelson sat with Rahm’s wife on the edge of the driving range at Torrey Pines as they awaited confirmation that it was job done, with South African Louis Oosthuizen coming up just short despite matching the leader’s last-hole birdie.
“It's pretty unique that just a month ago, I was there watching him win, and I was like, man, this is so cool,” said Rahm of Mickelson’s sensational success at the age of 50.
“For him to stay (at the end on Sunday) and come and congratulate me…. it shows we're really good friends.
“He made history and proved a lot of people wrong. In my little way, I made Spanish history and hopefully proved a lot of people wrong as well.”