In their last World Cup qualifying, the Republic of Ireland's second game ended in an embarrassing home defeat by Luxembourg - then ranked 98th - in March 2021.
While Tuesday's loss was not inflicted on home turf, it is equally chastening - and certainly as disastrous for the team's aspirations of returning to football's biggest stage.
Like the infamous Luxembourg game, the Republic of Ireland produced a woeful performance in Yerevan, with Armenia - thrashed 5-0 by Portugal on Saturday - richly deserving their win after continuously cutting Hallgrimsson's side apart.
Having fought back from two goals down to draw with Hungary, the Republic of Ireland should have had a spring in their step on Tuesday.
The opposite was true. While they started well and could have scored an early opener through Ferguson, they quickly ceded control and never regained it after conceding first for the ninth time in Hallgrimsson's 10th competitive game in charge.
Outside of Ferguson's goal, the Republic of Ireland rarely troubled the Armenian defence. Taylor and Chiedozie Ogbene, the two players drafted into the starting line-up, were taken off by Hallgrimsson at half-time, with even the introduction of Adam Idah three days after his late leveller against Hungary failing to spark them into life.
It could have been worse from an Irish perspective, too, had it not been for a couple of impressive Kelleher stops and a video assistant referee intervention cutting Serobyan's celebrations short.
Hallgrimsson may argue that, with four games to come in this campaign, there is still time for his side to turn things around.
But on Tuesday's evidence, this Irish team do not stand a chance of getting anything from next month's trip to Portugal, leaving them needing an unlikely combination of results if they are to earn a spot in the play-offs.
In addition to that five-goal thrashing by Portugal last weekend, Armenia's recent results include a 5-2 friendly loss to Kosovo and a 9-1 aggregate defeat by Georgia in their Nations League relegation play-off in March.
But against the Republic of Ireland, they looked comfortably superior in all areas and will probably wonder how they did not score more after having regularly troubled the visitors' defence.
Ultimately, it did not matter. Armenia can now savour a famous win and will be confident of securing a result when they visit Dublin next month, while Hallgrimsson - like his predecessor Stephen Kenny - will face difficult questions about his future after a demoralising start to the campaign.
Image source, Getty Images
