SUCH was Tiger Woods’ dominance of the game at the peak of his powers that you could often get longer odds on what colour of shirt he might be wearing on the opening day of a tournament than of him actually winning the thing. Fourteen majors in just over a decade show there was good reason for that. Bookmakers don’t drive big cars and live in fancy houses for nothing.

Of all his attributes, perhaps Woods’ consistency was his greatest strength. On four occasions in his career he would stride out to the first tee as the defending champion at a major and conclude the weekend having retained his title. Of his three Open championships, his latter two in 2005 and 2006 were won back-to-back.

That has not proved to be an easy thing to do in the modern era. Prior to Woods, you had to go back to Tom Watson’s successes in 1982 and 1983, then Lee Trevino in 1971 and 1972 and Arnold Palmer a decade earlier. It has been achieved just once more since Woods did it, Padraig Harrington defeating Sergio Garcia in a play-off at Carnoustie in 2007 then retaining his crown at Royal Birkdale.

“I think having won it the year before made it easier for me,” recalled the Irishman. “It’s harder starting off when you’re defending a tournament as on the first day you don’t want to mess up. But once you’re in there and playing well then you know you’ve already got one tournament in the bag and you’ve nothing to prove. You’re happy about your week as you’ve already put up a stout defence.”

Since then nobody has really come close to replicating Harrington’s achievement. Stewart Cink finished 48th a year after winning at Turnberry in 2009, Louis Oosthuizen could only reach 54th after his success at St Andrews, while Darren Clarke followed up his 2011 triumph at Royal St George’s by missing the cut. Ernie Els won his second Open at Royal Lytham in 2012 before finishing 26th a year on, Phil Mickelson prospered at Muirfield and then came 23rd a year later, while an ankle injury prevented Rory McIlroy from defending the crown he won at Royal Liverpool.

So now it falls to Zach Johnson - 12 months on from his play-off victory at St Andrews - to prove that winning then retaining the Open championship is not a near-impossible task. And at the halfway stage he is making a decent fist of it. An opening round of 67 was blighted only by bogeys on the last two holes, and it was a similar story during his second meander around Royal Troon on Friday, when his one-under 70 was tarnished by three dropped shots over the second nine.

Johnson, like his namesake Dustin, is a man of equanimous temperament. It is a calmness that served him well last year and will likely prove a useful attribute again over the weekend when he battles with the inclement weather and his own personal foibles. A five-stroke gap to leader Phil Mickelson will need to be overcome but Johnson does not come across as a man likely to stress unduly about making that happen.

“It’s as much about temperament as it is about technique out there,” he mused. “I feel like I'm in a good position and have control of my game for the most part. I think I'm also in really good control of my emotions and I’ve certainly got the mentality you've got to have to navigate a test like this. My game is right there, I’ve just got to finish it up. If I'm going to grade it right now, it's probably a B-plus at best. I still feel like my best game is in front of me. I feel confident in the sense that I'm doing the right things.”

In terms of being the defending champion, Johnson sees only benefits rather than pressures. History does not rate his chances greatly of retaining the trophy but, publically at least, it is not something causing him undue stress.

“It’s irrelevant,” he said with typical candour. “I really haven't thought much about it I've got to be honest with you. I guess that's probably a good thing. It's not like it's going to make it any easier or any harder. I've just got to go and compete.”

Harrington offered the American further encouragement. “Zach will be feeling nothing but good going into this weekend. He’s playing well, he’s in good form and having won it last year he knows how to close it out. That all goes in his favour.”