Speith lies in fourth place at 11-under, with Padraig Harrington fifth at St. Andrew's, finishing his round of 65 on 10-under.

Dunne and Harrington have both got themselves there after tearing up the course in their respective rounds, with Australian Marc Leishman the only player to better them, with a 64 to move into a tie for sixth.

They were not the only ones to do so, though, with Charl Schwartzel, Jordan Spieth and Danny Willett also levelling Dustin Johnson's overnight lead, before Dunne moved ahead and Speith then follower. However the man chasing a third consecutive major was passed by the leading trio late in the day.

Earlier, Graeme McDowell carded a third round 70. He's now on 2-under for the week.

Dunne is the first amateur since the legendary Bobby Jones to lead the Open after 54 holes, the American going on to lift the Claret Jug at St Andrews in 1927.

Three years later, Jones became the last amateur winner of the Open to date at Royal Liverpool and went on to complete the “Impregnable Quadrilateral” of Amateur Championship, Open Championship, US Open and US Amateur titles.

Paul Dunne shares @TheOpen lead after 54 holes. If it holds, would be 1st amateur to do so since Bobby Jones (1927). pic.twitter.com/99YpyqveFL

— ESPN (@espn) July 19, 2015

Dunne, who came through final qualifying at Woburn for the second year running, was in the second group out on Thursday and joked after birdies on the first two holes that he hoped someone had taken a screenshot to prove he had led the Open.

Three days later he had no such worries and could turn his attention from trying to win the silver medal for leading amateur to the Claret Jug.

“I don’t see why not,” said Dunne, who is a lowly 80th in the world amateur rankings. “I mean, I’m well capable of shooting the scores that I need to win if everyone else doesn’t play their best.

“Whether it happens or not, I can’t really control. I can just go out and try to play my game and see where it leaves me at the end of the day. Hopefully I play great again and post a good number.

“It’s surreal I’m leading The Open, but I can easily believe that I shot the three scores that I shot. 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!

“Hopefully I can do it again tomorrow, but whether I do or not, I’ll survive either way.”

Spieth is looking to become the first player to win the first three majors of the year and just the third to win any three in a single season – Ben Hogan won the Masters and US Open in 1953 but missed the US PGA to compete in, and win, the following week’s Open at Carnoustie, while Tiger Woods won the US Open, Open and US PGA in 2000 and completed the ’Tiger Slam’ in the 2001 Masters.

“It hasn’t come up in my head while I’ve been playing yet,” said the 21-year-old, who would also replace Rory McIlroy as world number one with victory.

“I can’t speak for tomorrow given it’s the last round and if I have a chance coming down the stretch, if it creeps in, I’ll embrace it. I’ll embrace the opportunity that presents itself.

“I don’t look at it as a negative thing, I look at it almost as an advantage. Why should it add more pressure in a negative way? If it adds more pressure, it just makes me feel like this is something that’s a little more special, let’s go ahead and get the job done.

“I know it’s easier said than done, but when you say added pressure, most people associate that with negativity or something that can hinder what’s comfortable. For me, I think it could be advantageous. You hit the ball a little bit further, you can really get your mind around a more specific target and block out other things.”

Paul Dunne Factfile:

• Started golf when he was 10 and began playing “properly” from age of 12.

• Now 22, he booked his place at the Open through final qualifying at Woburn, finishing ahead of the likes of Retief Goosen and Colin Montgomerie, having done exactly the same 12 months earlier to secure his debut in the event at Royal Liverpool. However, he almost missed his tee time for qualifying this year after not allowing enough time for the shuttle bus to get him to the 10th tee.

• Won the 2010 Irish Youths Amateur Championship title, following in the footsteps of Open champions Padraig Harrington and Louis Oosthuizen, who won his Claret Jug at St Andrews.

• Aiming to become the first amateur to win the Open since Bobby Jones in 1930. He is also in line to become the first Irishman to win the silver medal, awarded to the leading amateur making the cut, since a certain Rory McIlroy at Carnoustie in 2007.

• Graduated from the University of Alabama in business finance in April. Fellow Irishman Alan Murray coached him at university and is caddying for him this week.

• Plans to turn professional later in the year after the Walker Cup, which he is trying to qualify for having been included in a provisional 20-man squad.

• Wears same apparel as two-time major winner Jordan Spieth, whom he leads by one stroke, and has been mistaken for the calendar year Grand Slam-chasing American more than once this week.