There have been many voyages of discovery for Padraig Harrington since that time almost seven years ago when he gave up the Corinthian notion that golf is for amateurs and embarked on a journey where every putt had a monetary value.

He travelled into a closeted world where professional players pursued titles, and especially majors, with the zeal of missionaries; and where destiny called only the chosen few.

Yesterday, in the 131st Open Championship, and on a links hard by the Firth of Forth but softened by rain to have many of the characteristics of parkland courses, the Dubliner - who shot a second round 67 for six-under-par 136 - moved into a five-way share of the midway lead.

It has become increasingly familiar territory for him. In each of this season's two majors, the US Masters and the US Open, Harrington manoeuvred his way into challenging positions over the weekend. On each occasion, the great prize proved elusive: he finished fifth at Augusta, and eighth at Bethpage.

But, as he heads into the most important two days of his golfing life, Harrington remarked: "In some sick sense, I enjoy this. It's hard work, but I enjoy it. That's what I am here for, to get into positions like this . . . I have always known what I have to do when I get here.

"It is a question of being able to do it and, obviously, with experience, you get better and better at it."

He is halfway there, but the most difficult part has yet to come. "There is more than half the work yet to be done," remarked Harrington. In fact, the log jam at the top of the leaderboard is more congested than it ever was. On a day of persistent drizzle, but with a wind that was more an accompaniment than an obstacle, players used shrewd course management to inflict some remarkable feats of scoring which left 25 players within three shots of the lead.

Harrington, the leading European, was one of five sharing the lead at day's end, joined as he was by Ernie Els, Shigeki Maruyama and two Americans, Bob Tway and Duffy Waldorf. Harrington has been paired with Duffy for today's play. The second-last pairing of the day, they tee off at 3.20 p.m.

On what was a good day for the Irish competitors, Des Smyth showed no signs of fading away in recording a 69 for 137, just a shot adrift of the leaders. Darren Clarke, meanwhile, shot a 67 for 139 to be right in the thick of things and the only Irishman not to make the weekend was Paul McGinley.

And, in case any of those at the top had the impression they were rid of him, there was the ever-ominous presence of Tiger Woods - the player chasing the third leg of the Grand Slam - who shot a bogey-free 69 and finished up two strokes behind Harrington and his joint-leaders.

"I've stayed patient and plugged along," remarked Woods. "You play one golf shot at a time and this course is the epitome of that. You have to get the ball into play and from there you decide whether to be aggressive or conservative coming into the greens."

It was truly a remarkable day's golf.

Colin Montgomerie, a man who has never produced his best play on links terrain, defied such logic and played beautifully to shoot a course record 64.

And Els - one of those sharing the lead and one of eight major winners within three shots of that lead going into the final two rounds - had a front nine that contained a mere 29 shots. Only Denis Durnian, in shooting 28 on the front nine at Royal Birkdale in 1983, has managed better in a major.

The South African's blitz on the course featured seven birdies and two pars over that outward run, but the mental strain of continuing in that vein was demonstrated once he turned for home. He failed to record another birdie thereafter, and actually suffered two bogeys.

"It's quite difficult to keep it going. To play the front nine like that, you think you could shoot 54. It's a scary thought," said Els. Even for the very best, staying in the present can prove impossible.

Harrington had no such scary thoughts, and there was certainly no question of easing his way into the round: he had three successive birdies from the second - tapping in from 12 inches, four feet and four feet respectively after some exquisite iron play - and, after bogeying the eighth, he bounced straight back with a birdie on the ninth.

His strength of mind was further demonstrated on the home run when, after bogeying the 10th, he hit a sandwedge to the 11th green and rolled in a 20-footer for birdie. His final birdie came on the par five 17th, where his three-wood approach found the back of the green and he two-putted from 45 feet.

So content is Harrington with his game at the moment that he doesn't mind what the weather throws at him over the final two days.

"I'm happy with anything. I do think it would be a shame to play 72 holes of links golf without the wind, but it might blow me away as quickly as it blows anybody else away."

Of the five joint-leaders, only Els and Tway know what it takes to go on to win a major. But Harrington believes that he is mentally tough enough to go the extra step.

"No matter who you are, it always comes down to the mental side of the game. That's probably what Tiger is best at. But, in saying that, I think with the conditions you have that there are a lot of options in the way you can play, so you can play to your strengths mentally. It is easy to have a game plan out there."

While Harrington has become increasingly familiar with his position towards the top of the leaderboard in majors, such is not the case for Smyth. Yesterday, the 49-year-old - with one eye on the Seniors circuit - shot 69 for 137, to be just one off the pace in a three-way tie with Irish Open champion Soren Hansen and Carl Petterson in tied-sixth. These are lofty heights for Smyth, but his feet are firmly on the ground.

"I've jumped the first hurdle, and made the cut. Now, my next ambition is to stay in the top-15 and get an exemption for next year. After that, we'll see what comes. Anything else is a bonus.

"But, no, playing so well here won't make me delay my move into the Seniors. I hit the ball a decent distance, 270 or 280 yards. But when you're standing next to a guy that's hitting it 315 and he's hitting a six-iron onto a par five and you can't reach it, it is a huge advantage. I'm fed up with it, and ready to move on."

But not just yet. This weekend has some unfinished business to complete for Smyth and, like the rest of those in contention, he is lapping it all up. There is indeed much to play for.