They were teammates in the 1980s, firebrands for one of Australia's most storied rugby clubs.
Three decades on, Eddie Jones and Michael Cheika are bickering coaches with an often-gnarly relationship that could reach a crescendo this weekend.
England against Australia at a Rugby World Cup is always a must-watch - Saturday's quarter-final is the seventh meeting between the teams in just nine editions of the competition.
But the presence of two outspoken, fiercely passionate coaches in the corner for both teams adds to the allure.
In the white corner of England is Jones, a 59-year-old former hooker who considers pre-game barbs and mind games as a vital part of the build-up to a Test match.
In the green-and-gold corner of Australia is Cheika, a no-nonsense 52-year-old former backrower who also shoots from the hip and never takes a backward step.
When they clash, it can be explosive.
Just don't be fooled by some fairly gentle comments from Jones on Thursday, when asked for his assessment of the Cheika and the Wallabies.
"I'm proud of the job he does," Jones said. "He's a good old mate of mine."
It hasn't felt that way over the past three years.
Jones and Cheika go back a long way.
In the late 80s when they were players for Randwick, which has spawned a raft of great Australia internationals including Ken Catchpole, Mark Ella and David Campese.
Jones had a Japanese-American mother. Cheika was the son of Lebanese immigrants.
Solid pros for the Galloping Greens, neither ever went on to play for Australia.
However, they'd go on to be head coach of their national team, both losing World Cup finals but having plenty of success elsewhere in their careers.
They have only really crossed each other's paths in coaching circles since the 2015 World Cup, after which Jones became England's first ever overseas head coach.
Perhaps Cheika saw that as some sort of an affront
"It always hurts me when there's an Aussie over there," he said Thursday.
That might explain the antagonism between the pair that really kicked off in 2016.
During England's three-Test tour of Australia that year, which the visitors swept in unprecedented fashion, Jones said on arrival, in what felt very much like sarcasm, that Cheika was the "best coach in the world."
Cheika had been voted coach of the year in 2015 after turning Australia from a shambolic squad into a World Cup finalist.
Jones, who was coaching Japan at the 2015 World Cup, later added that he felt he was disrespected by Australia on his return to his homeland.
Whether he genuinely felt that, or it was simply a psychological ruse, Cheika bit.
He accused Jones of damaging his own "legacy" with his incendiary remarks about Australia, bemoaning his counterpart's "vitriol" toward the country where "opportunities were given to him to catch and grow up as a coach and play."
Cheika didn't like the way Jones organised a coaches' meeting with match officials ahead of Wallabies' game against England later in 2016 at Twickenham, which they lost.
"I wouldn't know him if I didn't play footy with him," Cheika said, referring to their Randwick connection.
"We wouldn't have associated."
Days later, Cheika said Jones "always operated with a chip on his shoulder." The following year, before another meeting at Twickenham won by England, they clashed over talking about referees to the media.
At this World Cup in Japan, Cheika couldn't resist reacting to some cheeky comments by Jones about the "typhoon gods" smiling on the English after their pool game against France was called off because of the destructive Typhoon Hagibis, therefore giving England an extra week of rest before the quarter-finals.
"So I suppose they'd better win," Cheika said.
"They've had the best preparation, according to the coach, so they'd better go out there and win."
There might be a healthy dose of respect between them for their abilities as coaches, and they may even share a glass of red wine after Saturday's match in Oita.
But it's clear these two strong-willed and uncompromising characters rub each other the wrong way.
Losing a quarter-final match at the World Cup will be painful enough for Jones and Cheika, who are unlikely to be in charge of their respective teams for the 2023 tournament.
Seeing their opposite number prevailing after their recent verbal jousting will make it a touch worse.
It was left to Jones to revive his and Cheika's Randwick past by referencing one of the club's recently deceased greats, Jeff Sayle, who has been praised for influencing the career paths of four Wallabies coaches - Bob Dwyer, Ewen McKenzie, Jones and now Cheika.
"There will be a bloke in the sky who will be quite excited about Michael and I coaching against each other this week," Jones said with a smile.
"I'm sure he's having a few beers next to St. Peter now, looking at the situation."
Australian Associated Press