Anyone seeking evidence that the All Blacks are capable of ending a 24-year wait to proclaim themselves champions of the world once again could do worse than take a stroll around Brad Thorn, who will play his final matches in the Rugby World Cup over the next few days.

At 36 years old, standing 6ft 5in and weighing in at a couple of pounds over 18 stone, the lock appears to have been hewn from the same batch of timber that produced the great Brian Lochore, New Zealand's captain in the 1960s, and his equally distinguished successor, Colin "Pinetree" Meads. These are totems of All Black rugby: impassive, raw-boned men who give the impression of having been reared in a remote region of a remote country, where self-sufficiency is the priority and words are not to be wasted.

Thorn has a voice, too, that seems to have been scraped raw by the winds of his native South Island – although his family left New Zealand when he was eight to settle in Australia, where he made a career in rugby league before switching codes, switching back again, and then making one last flip three years ago, in time to become a member of Graham Henry's squad for 2011.

He had the pleasure of taking a pass from his fellow lock Ali Williams and trundling over the line to complete the scoring in the quarter-final victory over Argentina at Eden Park last Sunday, becoming the oldest man to score a try in a knockout match in the history of the World Cup. It was his first in the competition since the play-off for third place against France in Sydney eight years ago, and he celebrated his achievement with characteristic understatement.

"I've got to say that one of my pet hates is organised try celebrations, especially when I see the guys waiting for the camera to get on them before they pull out their little moves," he said on Wednesday when asked whether he might venture something a little more extrovert were he to score against the country in which he has spent much of his life in Sunday's semi-final. "Emotion is great, but I'm a little bit old school, I guess."

If Thorn represents the traditional undemonstrative self-assurance of All Black rugby, a less confident side is equally visible in the buildup to the match against Australia. Thanks to the failure of five successive squads to repeat the achievement of the team coached to victory by Lochore in the first Rugby World Cup final, in 1987, a thick vein of anxiety is running through the current campaign. First exposed by the withdrawal of Dan Carter from the tournament through injury two weeks ago, it is now exacerbated by the doubts surrounding the fitness of Richie McCaw, the current captain – a different kind of totem from the Lochore/Meads template, but a totem none the less.

Long established as the world's best openside flanker, and the key to New Zealand's supremacy at the breakdown, McCaw is playing with a screw in his right foot, inserted to pin a stress fracture in February. Although claiming that he no longer feels any discomfort, he has not been taking part in the team's training sessions and it was noticeable in the match against Argentina that he was operating on the periphery of the game. At Wednesday's press conference the reserve flanker Victor Vito raised a few eyebrows when he unexpectedly discussed the contingency plans to cover McCaw's possible absence.

"With Richie it's been the same thing for a little while now, just managing his foot," Vito said. "We're trying to get our skipper back on the paddock. If so be it that he can't play, either one of Thommo [Adam Thomson, another reserve loose forward] or myself can fill in there. Just with the breakdowns, Thommo is pretty good and we can all make steals, even Jerome [Kaino, blindside flanker] as well."

Eyebrows were also raised when McCaw's understudy at the Crusaders, Matt Todd, was seen at training earlier in the day. The New Zealand Rugby Union, understandably, played down the reason for his presence. Darren Shand, the team manager, said Todd was not replacing McCaw or any other squad member in the immediate future and that the openside had been at the session as part of a forward pack to oppose the All Blacks, in accordance with tournament rules. The fears of a nation are unlikely to have been eased.

McCaw was present to lead the squad into a morale-boosting meeting in Auckland on Tuesday with a dozen of their 1987 predecessors, including David Kirk, the first man to lift the Webb Ellis Cup after being installed as captain following a hamstring injury to Andy Dalton on the eve of the tournament.

"This is probably the biggest game a lot of our boys have been involved in," Andy Ellis, the current squad's reserve scrum-half, said on Wednesday. "It was great to have the '87 All Blacks in. They were sharing some of their stories. They talked about the semi-final being such a big game and then the final takes care of itself because the week goes by so quickly and you're naturally so up for it."

Ellis realised that he was getting ahead of himself. "We're excited about this weekend, and for sure it's a really, really big challenge," he concluded.

They will certainly do better to think about 1987 than about some of the car-crash incidents that destroyed the hopes of the perennial favourites in some of the subsequent editions of the tournament. New Zealanders are trying not think about the mysterious bout of food poisoning on the eve of the 1995 final against South Africa in Johannesburg, the ambitious Carlos Spencer pass that the Wallaby wing Stirling Mortlock intercepted before dashing 80 metres to touch down in the ninth minute of the semi-final in Sydney four years later, or Graham Henry's fateful decision to remove a limping Carter from the 2007 quarter-final in Cardiff, a withdrawal that preceded a victory for France by two points.

On Sunday they will meet a side who won this year's abbreviated Tri-Nations championship. New Zealand won by 30-14 in Auckland at the beginning of August in the first of their two encounters before losing 25-20 in Brisbane three weeks later.

"We've learned from the Tri-Nations series and throughout the years that we've played each other that whoever wins the physical battle goes a long way towards winning the game," Kaino said on Wednesday. "Nothing changes for us. It's a matter of meeting the intensity that a semi-final is about."

And if New Zealand's World Cup jinx goes back to 1987, Australia's Eden Park hoodoo has deeper foundations. Their last win at Eden Park was in 1986, which may seem to add even greater weight to New Zealand's home advantage.

"A lot of us are very familiar with the ground," said Kaino, who went to school and university in Auckland and plays for the city's provincial and Super Rugby sides. "I love playing at Eden Park. But it's a semi-final, both teams will be firing, and it's going to be something that we probably haven't encountered before. But we take a bit of comfort from it being on our own patch."

Neither side has looked invulnerable. While the Wallabies rode their luck on the way to victory over South Africa in the quarter-finals, the All Blacks took a while to hit their stride against Argentina. In order to become the tournament's first three-times winners, Australia would also have to become the first to win the trophy after losing a pool match on the way. New Zealand, by contrast, are unbeaten. But although you would not guess it from the ageless strength of Brad Thorn's quiet voice, the weight of expectation, and of anxiety, hangs most heavily on the men in black.