SANDWICH, England - In case you haven’t noticed, when the heat is on, Darren Clarke is not your typical burbling cauldron of angst.

Oh, somewhere within that barrel chest or behind those mischievous Irish eyes, there is a festering need to add the Claret Jug to his long list of golf achievements. He even acknowledges that.

“The Open is the biggest and best tournament in the world,” he said Saturday evening, after shooting a round of 69 that ensured he would take a one-shot lead into the final round of the 140th British Open.

“Nineteen times I’ve tried and failed to lift the Claret Jug and (Sunday) I have an opportunity. But at the moment it’s just an opportunity because there’s a long way to go still in this championship.”

In a third round Saturday that served up an entire spectrum of weather extremes - from driving rain and bitter wind to dead calm and bright sunshine - Clarke and the others blessed with late tee times got the biggest breaks in a week of big breaks.

Clarke shot a round of one-under-par 69 to sit at five-under-par after 54 holes, one stroke clear of American Dustin Johnson. Another American, 22-year-old Rickie Fowler and 40-year-old Thomas Bjorn, from Denmark are another two shots back at two-under-par. Spain’s Miguel-Angel Jimenez and Lucas Glover of the USA are the only other players sitting better than par, both at one-under.

“Obviously if somebody had given me 69 before I was going out to play, I would have bitten their hand off for it,” said the gregarious Irishman.

“Saying that, we did get very fortunate with the draw. We got very lucky. We started off in terrible conditions, then it cleared up after four or five holes, so we got lucky with the weather again.”

But, as much as Clarke wants to win Sunday, this isn’t his first rodeo. He’s won big tournaments and been a lynchpin in a half-dozen Ryder Cups and there will be no crisis of confidence, no getting ahead of himself, as he waits patiently to walk onto the first tee late Sunday afternoon.

“I can while away the time very easily,” said Clarke. “That doesn’t bother me in the slightest.

“Tonight, I’ll probably go to Chubby’s (his agent Chubby Chandler). He’s got fantastic chefs in there and I’ll probably stuff my face and go to bed at about 10 o’clock and try not to drink too much.

“Tomorrow morning, I’ll probably stuff my face again. Then I’ll just relax and watch a little bit of the golf.”

It’s been a long time since Clarke got locked into such good form at a major championship and he’s revelling in it. Only his putting let him down Saturday, or he might be four or five shots ahead.

“That was about as good as I could hit it from tee to green,” he said. “On the green was not quite the same, to say the least.”

Clarke missed several short birdie putts but made enough to hold off his competition. Now, in the hours where self-doubt so often creeps into the thought processes of inexperienced players sitting on a lead, Clarke exudes confidence.

“A guy named Ken Brown (now a BBC golf commentator) told me something before my first Ryder Cup in 1997,” related Clarke. “He said ‘Don’t let your golf game determine your attitude. Let your attitude determine your golf game.’ My attitude is very good this week and it’s shown in the way I’m hitting the ball.”

Long-hitting Johnson will join Clarke in the final pairing. It is the third time in the last three years that Johnson will start the Sunday round in the last twosome.

At the 2009 US Open, Johnson melted down and shot 80. At the 2010 PGA Championship at Whistling Straits, he was assessed a two-stroke penalty on the 71st hole that sank his hopes.

“Obviously, I’ve been in this situation a few times,” said Johnson. “I think the more and more you get into that situation, the more comfortable you get.

“I know what to expect and I know how to approach it.”

So, too, does his opponent.