John Smit and Victor Matfield have done more than play international rugby together.
They have grown up together and watched each other get married and have children. On the pitch, they have shared in glorious highs and trying lows. After this Rugby World Cup they plan to retire together: as world champions.
South Africa's most-capped players and two of the great Springboks in the country's rich rugby history, Smit and Matfield have been ever-present for a decade, through World Cup triumph, Tri Nations titles and a series win over the British & Irish Lions.
Their national duties have also spanned coaches coming and going, controversial military-style training camps and World Cup and Tri Nations failures.
The pair of 100-Test veterans hope to lead South Africa to successive titles, a feat never achieved at rugby union's showpiece, in their final act as Springboks. Australia stand between them and a semi-final spot.
Smit and Matfield forged their relationship as young squad members at the 2003 tournament in Australia, when South Africa's build-up under the former coach Rudolf Straeuli was undermined by the controversial pre-tournament boot camp, "Kamp Staaldraad".
Since then, they have formed the best thrower-jumper line-out combination in the world, become the most-capped Boks in their positions and created a hugely experienced partnership that has won a World Cup and two Tri Nations.
South Africa count on them to lead the way to an unprecedented third world title.
"Victor and I, it's crazy. We've played a huge amount of Tests together," Smit said. "For me, it's just a special relationship. A lot of people always take Victor for granted. He's a phenomenal player and a great leader. He's been a pillar of strength for me. I've relied on him heavily throughout my time as captain and he's stepped up and provided."
Matfield said: "Myself and John are big mates. We've been playing together for quite some time now. It's about knowing each other's body language, knowing what's coming and that always helps. It's fantastic what the two of us have."
In the past two years, however, their experience has been sorely tested. The Springboks have just two wins from their past 10 matches against their southern hemisphere rivals New Zealand and Australia, and they have slipped to No 3 in the world rankings.
The 33-year-old Smit, especially, has come under fire for his place in the team. Matfield, while still world-class at age 34, is not as dominant as he was in the middle of the line-out. But Peter de Villiers, the coach, retains faith in his two leaders to inspire the team again.
"I trust both of them completely," De Villiers said. "I know their abilities and how they can read the game. I think we are in a better position than we were a few years back."
And praise for Smit and Matfield is universal in rugby. During this year's Tri Nations, Graham Henry, the New Zealand coach, said: "They've been great players, haven't they?
"They've both played over 100 Test matches for South Africa and John has probably been one of the greatest captains that's captained in the game of rugby. He's won a World Cup. He's a special man and a special captain.
"Victor has been and may be still the greatest line-out forward in the game. They're special players and we have a lot of respect for them."
With the experience of a combined 213 Tests, the pair said reacting to adversity and recovering when things go wrong will be key in the final days of the World Cup.
"I think that's what makes a good team," Smit said. "A team that can prepare itself well for a curve ball, but also react well to a curve ball. And this team has seen a few curve balls in its time. We've overcome a lot of them and some we haven't - it's those lessons where you haven't that you have to hold on to."
Matfield also stressed that the World Cup results would not be about only the two veterans.
"Not everyone's career is ending. The others will keep going, so the Springboks are still in good hands after the World Cup," Matfield told the Associated Press. "Of course, for the few of us that are going out there on a trip like this for one last time, we want to go out there and win. But I think everyone, even those who will continue afterward, they want to win the World Cup because it's so special."