It was the last time Mayo vanquished Dublin in the league; but they didn't just beat them, they beat them to a pulp.
So much so that, under the main stand in Elverys MacHale Park, the post-match candour of Pat Gilroy reached Doomsday levels.
"We have to regroup and sit down on Tuesday night and sort out a lot of things because, if they continue that, they won't be long in the championship either," warned the Dublin boss, having watched his All-Ireland holders lose by 12 points.
The outcome had been long decided before Dublin sub Paul Flynn and Diarmuid Connolly (for two yellows) walked. Flynn had lost a close friend to suicide in the preceding week. He would later realise that his head was in the wrong place for football that night.
But this 2012 NFL Division 1 refixture, in late March, wasn't merely a tale of Dublin disintegration.
It was the night Conor Mortimer, soon to be an ex-county footballer, became Mayo's all-time top scorer. The night they banished the bad vibes of three straight defeats to surge into league play-off contention. The night, some might even argue, they announced themselves as a heavyweight All-Ireland contender for the next half-decade to come.
"It was a Saturday night game and there was just something about it," remembers Mickey Conroy, who clipped the first two Mayo scores and finished with 0-4 from play.
"They say often you perform away from the lights so you can dance under the lights. And there was no doubt about it, we danced under the lights that night."
Tonight, Mayo and Dublin will tango in Castlebar again. All changed from that 0-20 to 0-8 rout: although since Mayo reprised victory in a roller coaster All-Ireland semi-final later that year, they failed to win any of their next 15 dates with Jim Gavin's Dublin. Now James Horan faces a new rival in Dessie Farrell, with no one expecting a lopsided repeat of 2012.
But for Mother Nature, it never would have come to this. The tie was originally fixed for February 11, and Dublin's initial dominance was barely reflected in a three-point interval lead. Only one problem: the fog.
Marty Duffy made the only call possible. Match abandoned. "We were going to get a hiding," Mortimer reckons. Only one thing to do for the frustrated tourists. "We got back to the hotel," Flynn recalls, "and all the lads were itching for pints and trying to figure out whether we were going to get out or not ... none of us had jeans or anything. Anyway, a long story short, we got out and had a bloody great night in Westport."
By the time battle resumed, Mayo were stuck on four points after five games; Dublin had six. But football, that week, was the last thing on Paul Flynn's mind.
"On March 25 my friend died by suicide," he explains. The Gaelic Players Association CEO has previously spoken about the tragic passing of Alan Leetch, his childhood friend, and how it prompted him to become involved in suicide awareness, fronting the Pieta House 'Mind Our Men' campaign.
But that particular week, emotions were raw.
"Pat (Gilroy) was so good, he was like 'Look, you don't need to come back this week' but I just wanted to get my mind off things," Flynn explains.
"I trained on the Thursday; I never was moving as well, I don't know what it was. And Pat said, 'I can't not bring you, you're moving well' … so I was happy to go and be a part of the group.
"Then I came on, and I obviously wasn't okay because I bloody did something ridiculous and I lashed out (at Colm Boyle), which there was no reason to do. Anyway, I always put it back to that game because, after that, I realised that I probably wasn't all right and I needed to get a bit of help."
It was 0-16 to 0-5 when Flynn lashed out. A massacre. The flip side is that Mayo were thrillingly in the zone.
"It was the first night we really went after (Stephen) Cluxton's kickouts," says Mickey Conroy. "If you go watch the game back, (Alan) Dillon picked up a couple of points from the actual high press on the kickouts. We went after it in a big way, trying to pin them in."
Profiting more than anyone was Mortimer, then studying in Dublin and friendly with several of their squad. His 0-8 tally (5f) matched Dublin's entire total and before half-time he had overtaken Joe Corcoran to become Mayo's all-time record scorer.
"Everything went my way. I was going for the record - everyone knew it was there," Mortimer recalls. "As a personal accolade it was good but, at the end of the day, it was a league game. I enjoyed it because I knew I was going back to Dublin."
Less enjoyable was the sequel: for the final regulation league round in Kerry a week later, he started on the bench. Was he baffled?
"I was. I was freaked - initially. And there was never really a reason given for it, but I don't want to get into it."
A few months later, again omitted from James Horan's team for the Connacht final, he quit the Mayo panel, never to return.
In his absence, Mayo became a perennial contender, reaching the All-Ireland finals of 2012, '13, '16 and '17.
Conroy harks back to that 2012 league game, saying: "We knew there was something changing in the group, and that was nearly the day we said, 'Hey, we're going somewhere here'."
Mortimer puts it succinctly: "They pushed on, we didn't."