Alfie Mawson ended Liverpool's 18-match unbeaten run by securing a surprise 1-0 triumph for the Premier League's bottom side Swansea City at the Liberty Stadium on Monday.
Centre-back Mawson's first-half strike gave Carlos Carvalhal his first league win on home soil since taking over as Swansea boss in December and handed Liverpool their first loss in any competition since they went down 4-1 to Tottenham at Wembley in October.
The Swans remain bottom despite the victory, though they are now just three points adrift of safety, while the Reds were unable to build on an impressive 4-3 triumph over runaway Premier League leaders Manchester City and regain third position from Chelsea, remaining fourth.
Liverpool gave £75million signing Virgil van Dijk a Premier League debut and it was the centre-back's header that eventually fell for Mawson to sweep in the opener in the 40th minute.
Klopp's side had plenty of chances to get on the scoreboard, Sadio Mane firing wide in first-half stoppage time and Mohamed Salah seeing his free-kick tipped over magnificently by the impressive Lukasz Fabianski.
There proved to be no way through for Liverpool, who saw Roberto Firmino hit the post with a header deep into stoppage time - Adam Lallana unable to convert the rebound - as they failed to claim a sixth straight win in all competitions for the first time under Jurgen Klopp.
Carvalhal deployed a three-man defence but a lofted pass from Emre Can - who was wearing the captain's armband - quickly bypassed it in the 10th minute, though Mane's first touch enabled Fabianski to come off his line and smother.
Van Dijk went close with a header before turning creator with a chipped pass in behind for Salah, who lashed a left-footed volley high and off target as it dropped over his shoulder.
Alex Oxlade-Chamberlain drilled an effort straight at Fabianski and Liverpool were punished for their profligacy five minutes before half-time. Van Dijk was unable to clear a corner sufficiently and, after the ball bounced off Federico Fernandez, Mawson fired just Swansea's second shot of the half into the bottom-left corner.
Mane had a chance to equalise in first-half stoppage time but he lost his footing as Salah's cross came in from the left and volleyed wide.
1 - Alfie Mawson's goal came from Swansea's only shot on target and second shot of any kind in the first half. Steal.-- OptaJoe (@OptaJoe) January 22, 2018
Liverpool found it tough to test Fabianski despite dominating possession after the restart, Salah curling outside the right-hand post before Kyle Naughton's excellent challenge denied Andrew Robertson a one-on-one with the goalkeeper.
When Klopp's men did get a shot on target they found Fabianski in fine form, the Poland international leaping to his right and pushing Salah's free-kick behind on the hour.
Lallana and Danny Ings entered the fray for the visitors, in place of Oxlade-Chamberlain and Georginio Wijnaldum, and the former Burnley striker forced Fabianski to make a save low to his left with a cross-goal effort 13 minutes from time.
Liverpool piled on the pressure in the closing stages but Can and Salah wasted stoppage-time opportunities before Firmino almost broke Swansea hearts.
The Brazilian had scored five goals in his last three Premier League appearances against Swansea but he was unable to add to his tally as his 94th-minute header came back off the upright and Lallana could not convert on the follow-up from inside the six-yard box.