ARSENAL 2 (Alex Oxlade-Chamberlain 16, Lukas Podolski 47)
LIVERPOOL 1 (Steven Gerrard 59-pen)
Three days ago, Liverpool were daring to dream of a first league title in 24 years and maybe a Double.
Today, they are glancing nervously over their shoulders at Tottenham tip-toeing towards them.
Nothing has changed and everything has changed.
A single Premier League victory over Arsenal didn't necessarily make Liverpool's season, but a single FA Cup defeat by Arsenal could break it.
Those are the slimmest of margins which the top four must contend with and the Reds have reason to be fearful.
Their patience is all spent. Their hallowed history is a handicap. The thought of failure this time around is crippling.
Liverpool's other rivals all have a silverware safety net to fall back on; another tilt at a trophy, either in London or Lisbon.
Their narrative doesn't just begin and end with the Premier league.
But it does for the Reds. Their colourful campaign has suddenly switched to black and white.
If they qualify for the Champions League, they succeed. If they fall short, they fail.
There is no middle ground left for Liverpool. Whatever middle ground remained collapsed like a sinkhole into the Emirates turf yesterday morning (Singapore time).
After Arsenal's unexpected 2-1 victory, the relative silence on social media among Liverpool's hardcore was damning.
The anxiety is inescapable; the unsaid possibility almost too much to take.
To get this close - this close - to achieving something special with the most swashbuckling Liverpool outfit since Barnes and Beardsley, only to end up with nothing, doesn't bear thinking about.
But the Reds are thinking about it.
They're doing nothing except think about it.
Manchester City have three other trophy opportunities to potentially assuage any Premier League pain.
Chelsea still have the Champions League. So do Arsenal.
The Gunners are also in the FA Cup quarter-finals, thanks to Liverpool.
For the Reds, there is no more sticking or twisting.
They're lumbered with the hand they've got, desperately hoping others fold before them.
Calculations are already being made and fixtures analysed.
March brings a date to Old Trafford and their biggest six-pointer of the season at home to Tottenham, while April throws up banana skins with the visits of both Manchester City and Chelsea.
None of these sides can afford to lose. Only Liverpool have everything to lose.
By the time May comes around, Crystal Palace and Newcastle may confirm a satisfying campaign or conclude the most soul-destroying season in years.
Right now, they are four points from history. They are three points from failure. The FA Cup loss has suddenly simplified their season.
Howard Webb's refereeing was exasperating and Brendan Rodgers was right to be aggrieved for the "blatant" penalty not given, but the Reds' flaws played into the pessimist's hands.
Liverpool's house is established on the foundations of Luis Suarez and Daniel Sturridge - and 23 goals in 24 appearances from the former and 19 in 21 from the latter suggest the club are building on solid ground. But they are human.
Sturridge, in particular, still succumbs to moments of erratic indecision.
It's a minor quibble, but a crucial one when there aren't major differences between the top sides.
His three missed chances against Arsenal in the tightest of contests proved that point.
So Liverpool's FA Cup exit leaves Suarez and Sturridge dancing on the thinnest of tightropes for the next three months.
They could still conceivably win the title. They could also miss out on the top four. One is unlikely, the other is unthinkable. Nerves will be shredded.
The Liverpool faithful can deal with the despair. Despair has dogged them for years.
But the hope must be killing them.
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