They are former club team-mates and kindred spirits, but coaches Michael Cheika and Eddie Jones are putting friendship on hold as they clash in Australia's intense Test series against England.
The two Australians stood out for their caustic wit and fierce competitive drive when they both played in the scrum for Sydney's famous Randwick club in the 1980s.
Three decades later, sparks could fly as the uncompromising Jones and Cheika meet in the Test arena, at the helm of England and Australia respectively.
Exchanges so far have been moderate, with Cheika, who played number eight for Randwick, refusing to rise to the bait set by the older Jones, who was hooker.
But given their reputations for candour and mind games, things could get heated during the three-Test series starting in Brisbane on Saturday.
"Both of them would never give in, never take a backwards step," recalled former Wallabies mentor Bob Dwyer, who coached them at Randwick.
"It is that sense of determination, but their other key character trait was this impish little boy's sense of humour and quick wit."
Much is at stake for Jones, who is hoping to lead Six Nations champions England to their first series win in Australia, a stepping stone to what he intends to be a second World Cup victory in 2019.
He set the tone immediately after arriving, when he suggested a broad campaign to unsettle the tourists after his bags were searched by customs.
Jones has also accused Cheika of playing "smoke and mirrors" and having "a lot of deception about him", comments that were dismissed by the Wallabies coach.
- Kindred spirits -
Cheika is also rebuilding after last year's World Cup, and is defending Australia's proud record of only three defeats out of 17 Tests against visiting England sides.
"It'll be a very exciting series both on and off the field," said Dwyer. "Eddie Jones is a bloody master at mind games, although Cheika ain’t too bad at them himself. It'll be a heck of a lot of fun off the field."
Both Cheika, 49 and Jones, 56, come from ethnic minority backgrounds, outsiders in a sport steeped in the world of private-school privilege.
Jones's mother is Japanese, while Cheika's Lebanese parents emigrated to Australia in the 1950s.
While Randwick, the 'Galloping Greens', have produced around 100 Wallabies and four national team coaches, neither Jones nor Cheika were capped for Australia.
Cheika, who took over the Wallabies at a troubled time from another Randwick graduate, Ewen McKenzie, in October 2014 and led them to the World Cup final a year later, says Jones is a kindred spirit.
"We did not come from established rugby backgrounds or traditional pathways," Cheika said.
"We both come from ethnic backgrounds so there are some similarities there. We were both outsiders. Perhaps not anti-establishment, but at least outside it and that gives you a different perspective."
Although often on the receiving end of Jones's wicked wit, Cheika said he could see that the indomitable hooker would make his mark in rugby.
"I always admired Eddie's style. He had that attitude but he also thought about the game," he said.
"You could see that he would be a coach because he was a leader. He always told us what to do, especially us younger fellas."
- 'King of the sledgers' -
Celebrated Wallaby fly-half Mark Ella, another who adorned the Randwick team of the time, grew up and went to school with Jones and is well versed in his antics.
"We have known each other a long time. Even back then Eddie was a very smart character," Ella said.
"He has an extremely witty, at times vicious sense of humour. He was the king of the sledgers. Oh, his tongue was lethal."
Dwyer added: "He calls a spade a shovel, Eddie. I consider myself a very direct Australian, but Eddie is more so than I am. He takes no prisoners at all."
Former Wallabies flanker Simon Poidevin recalls when the two incorrigible stirrers were at it in Randwick's match against the world champion All Blacks in 1988.
As Poidevin relates, Cheika asked Wayne Shelford: "Is that all you’ve got, mate?" while Jones was giving an earful to hooker Sean Fitzpatrick.
Naturally, Randwick lost the game 25-9, but that didn't stop the prolific sledging.
But away from the media and public spotlight, Cheika has promised his former team-mate a beer at the end of the series.
"That's what the game is about. But once the whistle blows, we have got nothing to do with it," Cheika said.
"He is older than me, so my culture tells me I have to pay respect to my elders."