They are two of Australian sport's most polarising talents, leaving fans divided over who to support when Nick Kyrgios and Bernard Tomic clash in the first round of the French Open.
Forget who backs who, though, Monday night's (AEST) showdown has been a long time coming.
The two former Wimbledon quarter-finalists have racked up some 511 tour matches between them, but never before have Kyrgios and Tomic gone head to head.
Not directly on court anyway.
They've traded plenty of verbal barbs, most famously when a frustrated Tomic, while losing a 2016 Davis Cup match to American John Isner, accused Kyrgios of faking illness to dodge the tie in Melbourne.
"Nick's sitting down in Canberra. Bullshit he's sick ... that's twice he's done it," Tomic muttered to Australian captain Lleyton Hewitt during a changeover.
Kyrgios was quick to hit back at his one-time US Open doubles partner.
"Let's not forget who holds the quickest loss on the ATP tour lol #howmanyminutesagain," he tweeted, referring to Tomic's 28-minute loss to Jarkko Nieminen in Miami in 2014.
Kyrgios removed the tweet but his replacement post ensured tensions would remain.
"Heat of the moment, not gonna take it personally ... Just don't expect me to have your back anytime soon."
The pair buried the hatchet to enjoy a jovial practice session in Paris last year before Kyrgios claimed "Bernie has lost his way" in a PlayersVoice column four months later.
"We were pretty good mates when I was younger," Kyrgios wrote. "I obviously didn't know the tennis tour too well back then and we were guys of similar age, representing the same country, on the road at many of the same tournaments.
"But a lot has changed since then. He needs to figure out what he wants to do. I can't relate to anything he says anymore.
"He says one thing and he does the other. And he contradicts himself all the time."
Bernard Tomic. Source: Getty
After an ongoing public row with Kitty Chiller before Kyrgios and Tomic sat out the 2016 Rio Olympics, Kyrgios said it was wrong of Australia's Games chief - and others - to "lump me in the same category as Bernard Tomic".
It's an easy leap to take, especially for casual followers who cast judgment primarily on the controversial antics that earn Kyrgios and Tomic unwanted headlines.
But they are two complex characters with contrasting personalities, Tomic laid-back and calm on court, Kyrgios explosive and intense. Lassitude versus attitude, as one observer put it at Roland Garros.
What the tennis enigmas offer up when they are lumped on the same court in Paris on Monday is anyone's guess.
They had been seeded to square off at the 2016 US Open. Instead Tomic was forced to apologise for telling a heckler to "suck my balls" during a spiteful 6-4 6-3 4-6 7-6 (7-0) first-round loss to Damir Dzumhur that scuppered hopes of an intriguing duel with his on-off sparring partner.
"I didn't give everyone what they wanted," Tomic said at the time.
Two years on and Roland Garros is abuzz in anticipation of the all-Australian tussle.
Their compatriots can't pick a winner - but most will be tuning in.
"I'll probably stream it," Daria Gavrilova said.
John Millman, the only player in eight matches to topple the resurgent Tomic over the past month and who also beat Kyrgios at Flushing Meadows last year, said he'd be watching too.
"Look, we both know that sometimes they divide opinion with the Australians," Millman said.
"But at the core of it also we both know that when they're playing at 100 per cent they can beat anyone all over the world.
"So hopefully they let their racquets do the talking and, if they do, they can both kick some massive goals.
"It will be an interesting one for everyone to watch, not just for guys back home but everyone here is interested to see how that one goes.
"I know I'll be watching the TV if I'm not playing."
