Portrush's Rickie Elliott walks with Brooks Koepka to the sixth tee during the final round of the 2017 U.S. Open at Erin Hills in Erin, Wis. on Sunday, June 18, 2017. (Copyright USGA/JD Cuban)

Caddie Ricky Elliott gave up on his tour dream to become a humble assistant pro but he never lost his love of the game and got the thrill of his life — and a $216,000 bonus — when he helped Brooks Koepka win the US Open at Erin Hills on Sunday.

The 40-year-old Portrush native was one of Ireland's top teenage amateurs in the 1990s, winning the Irish Under 16 Boys title in 1993 and the Ulster Boys in 1995 before going on to represent Ireland as a Boys and Youths international.

He enjoyed no shortage of success for the University of Toledo from 1997 to 2000, helping the Rockets qualify for the 1999 NCAA Championships.

He dreamt of becoming a tour professional like his boyhood friend and Orlando neighbour Graeme McDowell, but after giving up the mini tour grind, his decision to become an assistant at exclusive Lake Nona in Orlando put him on the road to caddie heaven.

"I sucked as a pro and it was the next best thing to go caddying," Elliott said in his Antrim lilt just minutes after Koepka's 16 under par demolition of Erin Hills.

"I played a couple of years on the mini-tours and I realised how tough it was. I grew up with G-Mac and I saw what he was doing. I mean, these guys are so good I am glad I gave it up.

"I was at Lake Nona for seven or eight years, as an assistant, did a bit of teaching and then the caddying opportunity came up with Maarten Lafeber in Europe for two years."

Brooks Koepka and his caddie Ricky Elliott as they walk down the second hole during the final round of the 2017 U.S. Open at Erin Hills in Erin, Wis. on Sunday, June 18, 2017. (Copyright USGA/Darren Carroll)

Elliott went on to work for former collegiate rival Ben Curtis for three years and loved every minute.

It was only by chance that he picked up Koepka's bag for the US PGA at Oak Hill four years ago and he didn't have to think twice when offered the bag full time.

"He had just come off the Challenge Tour — the lad who was caddying for him couldn't come to America — and his coach Claude Harmon asked if I wanted to come and caddie for this lad in the PGA," Elliott explained.

"It was the first time I had ever caddied for someone in a major, and I said absolutely."

The sight of Koepka blasting the ball down the range at Oak Hill was all Elliott needed to see to realise he had hit the jackpot.

Ricky Elliott looks on as Brooks Koepka hits his tee shot on the ninth hole during the final round of the 2017 U.S. Open at Erin Hills in Erin, Wis. on Sunday, June 18, 2017. (Copyright USGA/JD Cuban)

“He’s striping these shots,” Elliot has said of their initial meeting. “I’m like, ‘Happy days.’ I was still in Europe, but you know what it’s like when you see a good player.

"He made the cut that week, played with Tiger (Woods) on Sunday and said to me in the locker room, ‘Do you fancy doing a few in Europe?'”

It wasn’t a hard decision.

"Since that point he hasn't won as much as he should have on paper but he has always had the talent to pull off something like this.

"He has got a Major game obviously. He always thought he could win something big and probably hasn’t put away enough PGA Tour events to probably validate winning something this big on paper.

"But he is a major player; he hits it long, he does everything, he chips it well, he putts it well. Statistically, he should be contending in these things, and it is just about crossing the line for him, and he did it."

Elliott, a hugely affable character, became a US citizen in 2015, joking: “I had to say a sentence in English and I had to spell a word, and I just squeaked by that.

Brooks Koepka waves to the gallery after finishing his final round of the 2017 U.S. Open at Erin Hills in Erin, Wis. on Sunday, June 18, 2017. (Copyright USGA/Jeff Haynes)

“There was about 80 of us in the room and 2,000 people had come to watch. I was there on my own, sitting beside a wee Chinese man waving the flag. It was cool.

"I’ve spent half my life over here. You’re still always where you’re from, but I’m pleased as punch to be an American citizen.”

While he's friends with a host of top Europeans, Elliott went on to caddie for Koepka in last year's Ryder Cup win at Hazeltine and credits the experience as key to Koepka's emergence as a major winner.

The 27-year old Floridian felt like an underachiever despite winning the 2014 Turkish Airlines Open, the 2015 Waste Management Phoenix Open and last year's Dunlop Phoenix title in Japan.

"There is no doubt that experience helped him today," Elliott said of Hazeltine. "He is seeing all his peers do it and seen Dustin [Johnson] do it last year.

"Once you see one of your peers do it, it is a little like the G-Mac and Rory thing back in the day. If G-Mac can win the US Open, I am going to win it next year. That definitely helps."

Koepka's nerveless display down the stretch on Sunday was no surprise to Elliott who said he was more nervous winning the Irish Under 16 Boys at Warrenpoint 23 years ago.

Brooks Koepka poses with the trophy after winning the 2017 U.S. Open at Erin Hills in Erin, Wis. on Sunday, June 18, 2017. (Copyright USGA/JD Cuban)

"He was so in control of his game all week and there was no point we were worried," he said. "Obviously he needed to make a few things happen coming in to win the event but he stayed patient, and he came and holed a couple of putts and that was it. But he never changed from the first tee to the 18th green."

As for Elliott, the victory was a dream come true for a Portrush man who has been steeped in the game since childhood.

"I tried the teaching thing, I tried playing, I tried every other aspect to golf, but I really loved the competitive side and the gamble of going out there and playing," he said.

"If you miss the cut you go home, I love the competition of the golf and if you can’t do it yourself, this is the next best thing.

"It's been brilliant. Golf has been my life since I grew up in Portrush. It's what you do. I never thought after I quit golf that you could get the feeling of winning something and doing something great in golf. As I say, caddying is the next best thing and I've got that similar feeling."