Manchester City and Liverpool spent months staring each other down, waiting for one of them to blink in last season's Premier League title race.
As the absurd relentlessness unfolded week after week, neither budged and City's 98 points edged out 97 from the runners-up.
No one blinked. The question heading into Sunday's Community Shield encounter at Wembley is has this made them sick of the sight of one another?
"I went to university in Liverpool years ago and I remember Liverpool and Everton fans would ask 'are you City or United?'," Dan Burke, content editor for OneFootball and a contributor to the Blue Moon Podcast, recalled.
"I'd say City and they were like, 'oh, we don't mind City'. I think definitely Liverpool don't like City anymore.
"Both sets of fans know how to get under the other ones' skin."
We're off to WEM-BER-LEYYYYY!August 3, 2019
The reasons for football rivalries vary in each instance. Some are rooted in simple geography, others fester and mutate amid sporting competition and some exploded out of a controversial flashpoint.
They develop and evolve over time, which leads to the obvious question of what relationship do Manchester City and Liverpool share on the back of 2018-19's remarkable exploits?
Pep Guardiola and Jurgen Klopp share a deep mutual respect, which compels each to conduct themselves above the fray for the most part.
At his news conference ahead of the English season's traditional curtain-raiser, Guardiola declared himself "bothered" by Klopp's recent comments on City's spending capacity. Naturally, a few moments later he described his former Bundesliga foe as a "class manager, top manager… incredible".
Klopp and Guardiola might bristle occasionally but will never make a Jose Mourinho-Antonio Conte spectacle of themselves. Whether the same can be said of two fanbases where enmity appears to be growing is debatable.
"For me it seems like a faux-rivalry based on current events because we have two great teams who look quite sustainable in terms of what they want to achieve," said Nina Kauser of the Anfield Index.
"You had 2013-14, when City pipped us to the league and it was quite respectful. Maybe there was a turning of the tide when Raheem Sterling signed for City in 2015 and that made it a bit bitter for Liverpool fans.
"But as a whole, I really don't see it as a rivalry. I find it quite petty."
Burke agrees that the 2013-14 Premier League title battle and Steven Gerrard's fateful slip left a mark, but events have accelerated over the past year and a half.
Liverpool's rousing 4-3 win over City at Anfield in January 2018 handed the champions-elect the first defeat of their 100-point Premier League season.
Four S U P E R B strikes and an electric atmosphere.
to that memorable 4-3 win against tomorrow's opponents... pic.twitter.com/IZUSJWtkau— Liverpool FC (@LFC) August 3, 2019
Three months later, City were back on Merseyside for a Champions League quarter-final that began with smashed bus windows and ended in a 5-1 aggregate defeat.
Liverpool's defeat to Real Madrid in that season's Champions League final was then commemorated in a – to use Burke's description – "tawdry" terrace chant at City, which brought embarrassing PR when it featured fleetingly in the squad's 2018-19 title celebrations.
"I think the Champions League two legs is where it really began. That ramped it up – the arguing, the bickering," Howard Hockin of the 9320 Podcast explained, slightly wearily.
"I'm not going to go anti-Liverpool on you, but we'll think they were terrible and their fanbase is appalling and living on past glories. And they'll say different things about us.
"It's a different era now with social media, you see everything. I'm not going to judge a fanbase by what you see on Twitter because it's a very strange world where you live in a bubble.
"I went to a party at the end of last season and spoke to a Liverpool fan. You have a completely normal conversation.
"For all I know, I might have an argument with that person behind an anonymous user name the next day, saying ridiculous things."
Don't read the replies
Social media noise is undeniably a factor here. If long-standing rivalries should be aged and enjoyed like a fine whisky, the modern equivalents can often feel like someone throwing payday Jagerbombs down their throat before happy hour ends.
"I cannot be bothered with online bitterness in any way, shape or form. It's fundamentally boring," said Neil Atkinson from the Anfield Wrap.
"I genuinely don't care what Manchester City supporters are doing or saying. It bores me to tears.
"In terms of a sporting sense there is a rivalry between the two sides and the two managers. Thus far it's been intense on the pitch, but it's also been friendly.
"I think if you could offer both managers a magic button and the Community Shield was Manchester City versus Watford they'd probably take that.
"Whereas if you go back to the Liverpool-versus-Everton rivalry of the 1980s, or the classic Premier League rivalry of Manchester United versus Arsenal, those sides would have liked to play each other and kick lumps out of each other every week. That's where I think it's different."
The best of enemies
Everton and Manchester United. The can't-live-with-them, can't-live-without-them characters in this story who means all passions City and Liverpool direct at one another over the coming seasons might ultimately feel like a passing fling.
"We play Everton and it's massive and it dominates my life," Atkinson added. "It's psychologically huge.
"Everton could be 19th having not won in 10 and, if we were going to Goodison Park, it would be all I'm thinking about all week. That will never be the case with City and that's fine."
It's a position that Hockin and many of the thousands who will descend upon Wembley this weekend share.
"There's no doubt, if you ask most City fans they will say it has to be United who are our rivals," he said. "They'd have to be relegated for that not to be the case and go down three divisions.
"We've lived in their shadow for decades and five or six years finishing above them in the league doesn't change the fact that my whole lifetime it's been about United and getting one over them."