He stood out like a beacon. Not David Leadbetter, who was raving about the two amateurs in the Top 6 — co-leader Paul Dunne and American Jordan Niebrugge, who is three off the pace in sixth — but golf guru extraordinaire Dr Bob Rotella.

Forget that it's been three years since Harrington popped up out of nowhereville and almost won the US Open at Olympic Club in 2012, Ireland's three-time major winner and two-time Open champion is lurking. Seriously lurking.

That he shot a  seven under 65 was no surprise. That he hit it close, a lot, is impressive. That he holed a mile of putts under pressure was even more significant and Dr Bob looked excited even if there are 42 players covered by seven shots at the Home of Golf.

"He's great, he's in a wonderful place, I don't know how he could be any better," Rotella said as he headed out onto Golf Place. "He's been feeling real good all week and he's happy with everything. He's really got peace of mind, just playing his game, playing golf and keeping the pressure off himself.

"And when he does that he can play, as you see with his putter. He's putting well. And Paul Dunne... amazing." 

Harrington is full of admiration for the Greystones amateur — when he was 22 he was trying to win the North of Ireland during Open week. But it’s every man for himself in the final round of The Open and the 43-year old Dubliner is just two behind on 10 under after a sensational 65 that showed all the hallmarks of a man ready to win Major No 4.

Asked about Dunne's performance at the age of 22, Harrington bowed his head and said: ”It is phenomenal. His first-round score was a tremendous achievement, then to back it up and shoot another 69 in the second round was really gutsy. Now to go out there and be leading the tournament, you can't take that away from him ever. 

“He's led The Open Championship a long way into the event as an amateur. That is as rare as it comes. There's not too many people who have been leading into the third round as an amateur. 

“Hopefully he continues to play great. But as I said, tomorrow it will be all about me when I'm on the golf course in my own game. 

“If I don't win, I hope he does. But as I said, we're coming down the stretch, I'd be fighting for myself as much as anything else.

“It is nice to see another player coming out of Ireland, a young guy. I don't know him well or anything like that, but the little golf I follow, I know he's meant to be a very gutsy player, and it's nice to see.

“We had Shane Lowry win a Tour event as an amateur. It certainly wouldn’t be beyond belief to see him continue on and win it from here.”

Harrington was speaking as Dunne came down the stretch and the young Wicklow man got even better as the pressure augmented. But more of that anon

As for the two-time Open winner, he started the day seven shots behind  DustinJohnson on three under and played superb golf, picking up seven birdies with no mistakes to sit alone in fourth

Beaming afterward, Harrington said: “I always wanted to shoot 65 on the Sunday of an Open. Obviously there's another round to go tomorrow. Today was very, very important. 

“This is not a golf course that the leaders tend to come back on, so you really do have to be somewhat there or thereabouts going into Sunday. 

“I'm not sure of the forecast but if it’s a nice day tomorrow you're realistically talking 16-17 under being a possible winning score, so you ain't going to do that from 6- or 7-under. 

“So it was a big day to shoot a good score, to get yourself in contention. We'll have something to play for tomorrow.”

While Harrington contended for the US Open at Merion in 2012 but he’s had a miserable time in recent year, slumping to 371st in the world before winning the Honda Classic in a playoff on March 1.

He insists he’s a different man to the player who won three majors in 13 months and had to find a way to motivate himself again.

Trying to recall the last time he had a chance to win a major, he said: “I had a really good chance at the Olympic Club coming down the last at the U.S. Open on 2012. That’s probably my last really decent chance of winning. 

“I think I've found myself in a nice place so far this week, and regardless of what happens tomorrow, the attitude I've taken this week is the attitude I need to take going forward. 

“As I've always pointed out, I have to find a new way of playing golf. I’m not the person I was 10 years ago. 

"We all gain experience. We all gain some scar tissue with that experience, and you have to deal with who you are now. 

"I like the idea of it. I like the challenge. It’s a new challenge, and that keeps me motivated. 

“You can’t win your first major a second time, but I’m sure enjoying trying to find a new way of playing golf with the new person I am.”

Dunne's performance was otherworldly considering the context but he's somehow managed to live the cliché of "one shot at a time" and play his normal game.

As Jordan Spieth explained afterwards, once the modern amateur gets over the early nerves and finds his feet, he can perform at this level.

Q. Jordan, how surprised or not surprised are you that in such a major professional tournament we've got two young amateurs, one from Ireland and one from America, right up there in the top six?
JORDAN SPIETH: I would say I'm not extremely surprised. I think in years to come, you're going to see more and more of it. The amateur game has changed to be more like the professional game in the way that there's more tournaments, there's better golf courses, harder golf courses and better competition. That's what I felt like when I was playing junior golf into amateur golf. It was almost a mini-PGA Tour. By a mini-PGA Tour, it's just less events in junior golf, then you play a little more in college and amateur golf, and then you come out on Tour and step it up another level. But they're still playing -- there's some great players. There's guys that -- there will be an amateur that wins a PGA event or something like that, possibly even a major, I think, at some point in the next decade or so just because the game in amateur golf across the world now I think is getting more diverse and more intense, and I think it's awesome for guys to step up and do this.

Q. They seem so calm.
JORDAN SPIETH: Yeah, I haven't seen any of it this week, but I've certainly experienced it, whether myself or through others in majors. Not me in majors as an amateur, but seeing other guys do it. There's just no fear. They're just coming in with no fear and being able to really settle in. I think getting off to a good start is really important for amateurs playing in a professional tournament, just given, they're like, okay, well, now it's a new situation, now I've managed what happened, now I know I can do this, and I think that's what these guys did, they got off to a good start, and from there they know they can attack the course. To me it's not much of a surprise. I think it's awesome. I think it's an incredible experience in order to have that confidence once they do decide to turn pro if they decide to turn pro, and we certainly expect them to make a run tomorrow and don't consider them really falling off at all. I think it just adds to the amount of guys you have to beat.

Only one person truly believes that Dunne to go on and win The Open today and his name is Paul Dunne.

The Greystones wonder-kid grabbed a “surreal” share of the lead and those who know him are convinced he won’t beat himself.

Fellow Greystones Golf Club man Alan Murray is on his bag and knows him better than most as his former coach at the University of Alabama Birmingham.

Before the event even started, Murray said: “You root for those guys - the ones who go about it the right way... he’s one of life’s winners.

“Mentally he is very strong. For want of a better term, he’s one tough cookie and he will rarely beat himself.”

Dunne, 22, shot a bogey free 66 to make history by becoming the first Irish amateur to lead The Open at the end of a round, shaving a stroke off the lowest Open round by an amateur on the Old Course.

He shares top spot on 12 under par with 2010 Open champion Louis Oosthuizen and Aussie ace Jason Day with the reigning Masters and US Open champion Spieth lurking just a shot behind.

With Harrington only two back on 10 under, Dunne has every right to run and hide. But he’s cool as a cucumber after smashing the 54-hole record for an amateur in the Open by five strokes — after all, he’s one of the best amateurs in the world.

Confessing he’s a little out of his comfort zone, Dunne gave a reporter, who wants to know if it was "surreal" he was leading, the answer he wanted.

“Yeah, it's surreal I'm leading The Open, but I can easily believe that I shot the three scores that I shot," he said in a packed media centre environment normally reserved for the likes of Rory McIlroy or Harrington, or Graeme McDowell.

“If we were playing an amateur event here, I wouldn't be too surprised by the scores I shot. It's just lucky that it happens to be in the biggest event in the world.”

That comment brought some laugher but Dunne's no joke.

“Hopefully I can do it again tomorrow, but whether I do or not, you know, I'll survive either way,” he said in a demonstration of his cool, clear way of thinking things through.

After a round featuring six birdies and no mistakes, he confessed that to lead a major into the final round in just his second professional event, is amazing.

But he still has work to do on an incredible leaderboard where the top 32 players are covered by just six shots and the top 17 by just four.

He said: “It’s something I'll look back on and think is cool, but mid-tournament I'm just going to keep trying to focus on playing my shots and getting ready for tomorrow and just playing the best that I can, really.

“It feels great. I felt like I had so much support from the crowd today. I kind of felt like I was at home. Every shot I hit was getting cheered from start to finish, so big thanks to the crowd out there. 

“They kept me lifted the whole way through. It was great to play with Louis Oosthuizen today. He's obviously a great role model for me, great player, someone I look up to. 

“He was a really nice playing partner, so yeah, just really enjoyed it. It was such a fun day.”

As Harrington blasted seven birdies in a 65 to set the target at 10 under put himself in position to win Major No 4 and his third Open, overnight leader Dustin Johnson crashed to a 75 that left him five behind the leaders.

With Murray playing a blinder on the bag, Dunne forged ahead.

He birdied the first from two feet, the fourth from 15 feet and saved par after hitting his first bunker of the week at the fifth.

A birdie from 50 feet off the green at the seventh got him to nine under and the then birdied the ninth from five feet to get within one of the leader.

When he birdied the 10th from 15 feet, he was 11 under par and leading the Open but there was more to come as he went shot for shot with Oosthuizen, who won the Claret Jug the last time at St Andrews.

Four pars followed before he hit a 167-yard seven iron to 20 feet at the 15th and rolled in the putt to lead the Open on his own.

He even hit a high cut tee shot over the corner of the Old Course Hotel at the 17th that scared the living daylights out of his South African playing partner.

His approach, a four iron from 220 yards to 20 feet, impressed Oosthuizen even more.

“He's played unbelievable" the South African said. "That second shot on 17 was one of the best I've seen. Can he win? Absolutely. The way he played today, definitely.

"I think obviously everyone within three, four shots has got a really good chance of winning, and it's all about composure now and tomorrow really your thought process on how you're going to handle the pressure.”

Dunne targeted a 69 going out but when he turned in 32, he lowered his target to 66.

Asked how he’d approach the final day, he said: “I think it'll be the same as the last three days, just look at the weather, see what the weather is going to throw at us and then put a number in my head that I think I need to shoot. 

“I'm not really going to think about winning or where I'm going to finish until the last few holes. 

“If my strategy needs to change a little bit. But yeah, I can't control what other people do. Everyone could go out and shoot 63 or everyone could shoot 75. 

“All I can do is control committing to my shots and hopefully leaves me in good stead at the end of the day.”

He's a man in demand even if he isn’t a man with a grand plan for the professional ranks just yet.

While the future of players like Rory McIlroy and Jordan Spieth was decided or at least outlined long before they signed professional forms, Dunne has no agreements with any agents or representatives just yet

That wouldn’t be against the rules of Amateur Status as top amateurs can now sign pre-contracts with agencies as the finish up their amateurs careers.

And while Dunne might be wearing an Under Armour cap and top rather than the UAB or Golfing Union of Ireland uniforms he’s sported for the last few years, he hasn’t signed with anyone just yet.

Winning The Open would likely end his interest in the Walker Cup this September and there were at least three player agents lurking near the scoring area after his round. Some had other business there but they were also making sure they were present to spot the movers and shakers.

The family has received “a couple of calls” in the last few days but for now, they are just pinching themselves at the thought that he could win The Open.

His father Collie, mother Michelle and brother David were with him every step of the way yesterday as was his sister.

His father, a former amateur rugby start with Greystones, admitted that cardiac arrest was never far from his mind as his son surged into the lead.

“It’s that kind of feeling,” Dunne Snr, a financial controller in The Irish Times, said of the day. 

“Your heart is pumping so much you are looking actually for somebody to jump start your heart again. Those are type of feelings you get.

“It is a lot easier when you are out on the course and you can see the shots but the excitement is tremendous - the roars from the crowd, the excitement when the putts go in — it’s amazing.”

A huge posse from Greystones followed the 22-year old across the links with the head professional Karl Holmes leading the way.

“All the members and the pro from Greystones are out,” said Dunne Snr, who admits that his youngest son is a hard worker. “Paul always been a hard worker from day one though I’d say he gets it from his mum, Michelle.

“I played ruby but Paul always played a few sports - football and gaelic and tennis too. But golf took over. 

“When he decided to go to UAB it was hard to say goodbye but the fact that Alan Murray from our home club was there made it a lot easier. He’s an incredible guy, a super coach and a great caddie. They are having a lot of fun.

“He went to Alabama to push on with his game and the fact that Graeme McDowell had gone there was just a bonus.

“He works hard in the gym. physically he works hard and gets up at six am. Nobody works harder than he does himself.”

As Dunne was coming into the Media Centre for his press conference, he was congratulated by Des Smyth, who is working for BBC Five Live.

“It’s marvellous what he is doing,” said Smyth, who had chances to win the Open in his heyday. “And it’s been done before by Bobby Jones. 

“How will he feel? It’s very exciting. And he’ll be up for it. He will be nervous sure, but he’s young and he’ll enjoy it. It’s a wonderful buzz.”