Ireland's task in this group was never going to be easy, but it's suddenly become almost impossible.
Giovanni Trapattoni's side will have to pull off a stirring string of results now after a defeat that very quickly dampened some of the fanciful talk about replicating Greece of 2004. Now, they look much more likely to replicate Greece 2008: out in the first round.
Here the inherent flaws in the Italian manager's otherwise efficient system were exposed. Only a week ago, he spoke of potentially altering his system to prevent his two-man midfield being exposed by more fluid, modern formations as had happened against Bulgaria, Russia, France and Hungary.
Ultimately, though, he refused to budge from rigid 4-4-2 and suffered the kind of slips that produced a result like last night, against a Croatia who themselves were not completely convincing.
Slaven Bilic promised before this game that his team would alter their usual counter-attacking game in order to get at Ireland. Within minutes, Croatia had already put together ominous interchanges to pull Ireland apart.
On three minutes the devastating Darijo Srna skipped down the right to beat the often-suspect Stephen Ward. Srna put his cross in well from an awkward position and, although Mario Mandzukic first stumbled on the greasy surface, he then used it to his advantage to send a well-judged header skipping past Shay Given.
That silenced what had been a raucous Irish crowd and, for a time, seemed to shellshock the players. But they fought back to level on 19 minutes through that template of the Trapattoni era: a set-piece. Vedran Corluka was outfoxed by Sean St Ledger in the box, with the Leicester defender stooping superbly to head home Aiden McGeady's exquisite free-kick.
Over the next 25 minutes, Croatia grew in cohesion. The ball bounced kindly for an offside Nikica Jelavic, who expertly dinked the ball past Given. If Croatia created their own luck there, they got it again just after half-time when Mandzukic rose superbly to head against the post – but cruelly it rebounded off Given's head and in.