One word was prevalent ever since Shane Lowry surged into contention at The Open this weekend. Oakmont.

"Oakmont was so long ago and I was a lot younger," Lowry said after moving into a co-share of the lead on Friday.

"I feel like if I get the opportunity this week I'll be better. It definitely won't affect me, what happened in Oakmont."

Amid the chanting, raucous cheers and sheer euphoria that greeted Lowry walking off the 18th green at the conclusion of the greatest round of his life at Royal Portrush on Saturday, there was an unsettling sense of deja vu due to his four-stroke advantage.

Three years ago, Lowry held the same lead going into the final 18 holes of the U.S. Open. He had one hand on the trophy, a major breakthrough in his grasp.

Yet in golf things are never that simple and that fateful Sunday just outside of Pittsburgh was dragged back to the fore for Lowry this week.

The pressure of holding a significant lead in a major for the first time was evident. Lowry never recovered from a difficult start at Oakmont and struggled to a six-over 76, eventually finishing three shots adrift of Dustin Johnson – who himself had to endure a nervy penalty-shot controversy to win what is to date his only victory in one of golf's big four.

However, at Portrush, Lowry only fleetingly betrayed his insistence that no mental scars remained from the most painful of experiences. A wayward drive down the first and an approach into the greenside bunker leading to an opening bogey would surely have had his heart rate skyrocketing.

Lowry is a different man to three years ago, though. He has a young daughter, Iris. His priorities and perspective have changed.

"If I'm sitting here this time tomorrow evening it will be one of the biggest things that ever happened to me, there's no denying that," Lowry commented in a news conference on Saturday.

"But I just felt at the time in Oakmont my golf meant a lot more to me back then than it does now. I'm not saying that it doesn't mean everything, it's my career. But I've got certain things in my life that make it different. I've got family now. No matter what, my family will be waiting for me."

It has been a long journey back to this point. After missing the cut at last year's Open, for the fourth time in succession, Lowry slumped to a ranking of 92nd. 

Following the first round at Carnoustie 12 months ago, there was a pretty blunt declaration from Lowry.

"I'm not enjoying my golf at the minute, and my golf is not really enjoying me and that's the way it is, and it's hard to take," he said.

There was a recognition change was needed. Lowry split with long-time caddie Dermot Byrne in September and there has been a huge upturn in fortunes with new man on the bag Brian 'Bo' Martin, who grew up around two hours away from Portrush in Ardglass.

Victory at the Abu Dhabi HSBC Championship in January, after which an emotional Lowry spoke about a "tough couple of years on the golf course", preceded top-10s at the RBC Heritage, US PGA Championship and Canadian Open.

"With Bo I find I play golf now like there's no consequences, you know what I mean? You need to hit shots like there's no consequence," explained Lowry.

"What's the worst thing that can happen? If I swing the club here and hit the ball, no matter where it goes, what is the worst thing that can happen to you? That's kind of the mindset he brings into it. That's when I play my best. That's the way I am. I think we gel together nicely that way.

"I think as a golfer you have such a long career, well, hopefully you have such a long career, I've been [a professional for] 10 years now and it's just a rollercoaster.

"I think the reason I'm so good mentally now is I feel like I know how to take the downs."

There was no bigger down in Lowry's career than Oakmont three years ago. Now, standing a Champion Golfer after an astounding six-shot victory, there is no greater high.

That it should happen at Portrush, an Irishman winning on Irish soil, makes it only more special.

It was for so long unthinkable the tournament could be held here as the days of the Northern Ireland conflict, a period of history known as The Troubles, devastatingly split the country.

But this is a different time and there was a wonderful buzz around Portrush as home hero Rory McIlroy prepared to begin the week as one of the favourites for glory.

McIlroy, of course, did not even make the weekend and it was instead left to Lowry, from County Offaly in the Republic of Ireland, to slip under the radar and earn the acclaim of an adoring crowd.

He will, at some point after what will no doubt be a hefty celebration, go to bed with the Claret Jug, fresh in the knowledge the demons of Oakmont have been truly banished.