Jon Rahm made tension-packed long birdie putts on the last two holes on Sunday to win the 121st US Open and capture his first major title, defeating South African Louis Oosthuizen by one stroke.

The 26-year-old Spaniard curled in a spectacular birdie putt from just inside 25 feet at the par-4 17th hole then made his fourth birdie of the week at the par-5 18th, blasting out of a bunker and rolling in an 18-footer to seize the lead.

“I have a hard time explaining what just happened because I can’t even believe I made the last two putts,” Jon Rahm said.

After stunning, fist-pumping putts to reach the clubhouse, Jon Rahm could only watch 2010 British Open champion Louis Oosthuizen play the last four holes.

At 17, Oosthuizen sent his tee shot left into bushes and made bogey to fall two adrift and a closing birdie only made him a major runner-up for the sixth time in his career.

“I played well. Just fell a little short again,” Oosthuizen said.

“Jon played a great round of golf. Errant tee shots on 17 just cost me. I fought really well to stay in it and just fell short again.”

Jon Rahm fired a four-under par 67, the only leader to go bogey-free on the back nine, to finish 72 holes on six-under 278 with Oosthuizen on 279 and American Harris English third on 281.

“He was a major champion in waiting. It was just a matter of time,” four-time major winner Rory McIlroy said of Rahm.

“To shoot 67 out there was a really good round.”

On the same course where he won his first PGA Tour title in 2017, Rahm became only the fourth US Open winner to close with back-to-back birdies, matching Jack Nicklaus, Tom Watson and Ben Hogan.

“It’s incredible that I finished the way I did,” Rahm said.

“Making that putt on this green when I got my first win, it’s hard to describe.”

He became the first Spaniard to win a US Open and the fourth to capture a major title after Sergio Garcia, Jose Maria Olazabal and the late Seve Ballesteros.

“This was definitely for Seve,” Rahm said.

”I know he wanted to win this one most of all.”

Rahm won on his first Father’s Day as a dad at the same course where he proposed to wife Kelley, who gave birth to their first child, Kepa, in April.

“You have no idea what this means,” Rahm told his infant son as he hugged his wife in celebration.

Third-ranked Rahm also became the new world number one after top-ranked Dustin Johnson shared 19th on 286. Rahm topped the rankings briefly last year after winning the Memorial, but tested positive for Covid-19 during the event two weeks ago and spent last week in quarantine.

“I’m a big believer in karma and after what happened a couple weeks ago, I stayed really positive knowing good things were coming,” Rahm said.

“I got a breakthrough win here, my parents were able to come, I got out of Covid protocol early – I just felt like the stars were aligning and I knew my best golf was to come.”

At 17, Rahm curled the tension-packed putt from left to right with six feet of break, watched the ball fall into the cup and punched the air with his right fist.

Rahm went to the 18th hole, the easiest finishing hole in US Open history, and delivered an amazing putt and a right fist uppercut.

Rahm had seven prior top-10 major finishes without a triumph, including a share of third at the 2019 US Open.

The world’s five top-ranked players and four-time major winners Rory McIlroy and Brooks Koepka were within three strokes of the lead early as the tension grew.

But one by one, the rivals faded, leaving only Rahm and Oosthuizen to grind out pars into the final holes.

Defending champion Bryson DeChambeau had two bogeys and two double bogeys on the back nine on his way to a 77 to share 26th on 287.

Four-time major winner McIlroy made bogey at 11 and double bogey at 12 on his way to a 73 to share seventh on 283.

American Collin Morikawa, who took a double bogey at the par-5 13th, and four-time major winner Koepka, who closed with bogeys at 16 and 18, shared fourth with Italy’s Guido Migliozzi on 282.