Steven Alzate's first Premier League goal dealt another blow to Liverpool's title defence as Brighton & Hove Albion eased their relegation fears with a stunning 1-0 win at Anfield.
Liverpool had seemingly got back on track with successive away wins in London, but a second-half strike from Alzate gave Brighton a first victory over the Reds since January 1984.
The toothless champions ran out of ideas as the well-organised Seagulls left Jurgen Klopp's side without a goal in three home games and seven points behind leaders Manchester City - who they play on Sunday.
Burnley ended Liverpool's 68-match unbeaten home record in the top flight a fortnight ago and they have now lost two in a row at home in the league for the first time since September 2012.
Mohamed Salah wasted an early chance to put the Reds in front when he lobbed over the crossbar after Jordan Henderson picked him out with an incisive pass.
Lacklustre Liverpool could not find a way through a well-drilled defence and Dan Burn spurned a glorious opportunity to put Brighton in front, scooping into the Kop after Neal Maupay showed great composure in the penalty area.
Solly March was also off target with a curling effort, with Brighton not resembling a side battling to avoid the drop in a drab first half.
The champions posed much more of a threat after the break but they were stunned when Alzate opened the scoring with the first shot on target in the match after 56 minutes. Burn made amends for his earlier miss by heading a deep cross into the path of Alzate, who converted from eight yards out.
Brighton lost March to injury before Salah missed a good chance to equalise after Klopp had introduced Alex Oxlade-Chamberlain and Divock Origi, with Liverpool's frustration mounting.
Caoimhin Kelleher, in for the unwell Allison, prevented Pascal Gross from doubling the lead with a fine save and then also denied Leandro Trossard with a sharp stop, though one goal was enough for the visitors in the end.