Steven Alzate's goal was the decider the other side of the interval, the Colombian directing the ball home after latching onto Nat Phillips' clearance via Leandro Trossard.
Liverpool, lacking the desire they picked up on their travels to London, returned to their recent ways of stale and uninspiring football and were met by an indestructible back line.
Concerns will rightly be raised after more points were dropped against a team in the bottom six ahead of a make or break fixture at home to Manchester City this Sunday.
Sharpness in attack vanishes
After two fine performances in their back-to-back trips to London, a big sense of 'Oh no, here we go again' arrived when watching Liverpool in the first half, with not one shot on target registered.
A tame performance from those in red but a defensively astute one from Brighton, at times sitting back and enabling Liverpool have the ball combined with an appropriate mix of pressing.
Salah showed he had the beating of Burn and Adam Webster on the right flank, squandering a chance to continue on from his brilliant performance against West Ham by firing over after a typically deft first touch in the first half.
Liverpool then had no greater impetus in after conceding in what was becoming an unwelcome return home.
After contributing to nine goals in his last seven meetings against Brighton, Salah was wide of the target again- unable to tame a pacy Alexander-Arnold ball into his feet with a first-time shot.
For all the talk of moving Thiago Alcantara forward up the pitch, the midfielder had a comparatively subdued outing- it is becoming quite clear from recent performances, rather bemusingly, that Diogo Jota has been the most missed man on Liverpool's physio table.
The return of a lack of cutting edge and accuracy in the search for the killer pass throughout the game will set alarm bells ringing in preparation for a season-defining match this Sunday afternoon.
Just when you thought Michael Edwards' reputation couldn't have been enhanced any more, he secured the services of two new centre backs in Ozan Kabak and Ben Davies on deadline day for a combined initial total of £3million.
While neither featured against Brighton, Jordan Henderson and Nat Phillips once again performed admirably at the back, the latter of which particularly looking assured in clearances and in one-on-one chances.
The question was raised whether Ben Davies would be to required to fill in from the bench and move the captain further forwards in order to reignite an otherwise dormant midfield at the break.
Caoimhin Kelleher's contribution to keeping his team in the game should not go unnoticed, doing just enough to parry a Pascal Gross shot away from Ben White and reacting well to a thundered Trossard strike in the second half (not to mention an Alisson-Esque bullet-headed clearance learned on the training grounds of Kirkby).
The Brighton rocks
Lewis Dunk absorbing pressure in his own box early in the second half with two big blocks from an Andy Robertson cross and Firmino effort respectively set the tone for Brighton's defensive solidity in the second 45.
Adam Webster was a standout- ushering away any efforts towards goal from the Reds' elder statesmen up top with ease.
Man of the match-elect Webster registered 9 clearances, 5 possession gained possessions along with 100% aerial duels won and aided in extending his side's clean sheet record to four consecutive league games.
Brighton, now with just one loss in their last eight in all competitions, sit pretty with a 10-point buffer between the relegation zone.
Winning three of their last four, there will rightly be cause for optimism that displays such as the one at Anfield will keep the Seagulls in the top flight for another season yet.
As for Liverpool, the hopeful return of Sadio Mane and Fabinho will be a jab in the arm (no pun intended) upon arrival of the barnstorming Pep Guardiola and co. (whose last loss came on November 21 against Spurs).
Striking a balance of introducing fresh faces Ozan Kabak and Ben Davies in order to push the Fabinho and Henderson into midfield, the influence of the latter being particularly missed, will be something that weighs heavily on the mind of Jurgen Klopp.
It's remarkable given the injury crisis-stricken on those at Anfield this season that Liverpool are even mentioned in the title race at this stage, but the next week or two is a crossroads in Liverpool's season; sink or swim; adapt quickly, or fade away.