Ollie Watkins struck a first-half hat-trick and Jack Grealish starred as Aston Villa claimed an incredible 7-2 victory over Premier League champions Liverpool on Sunday.
Liverpool were without first-choice goalkeeper Alisson due to a shoulder injury and paid the price for some shambolic defending at Villa Park, with John McGinn adding to Watkins' treble in a rampant opening period for Dean Smith's men.
Mohamed Salah doubled his tally either side of deflected goals for debutant Ross Barkley and Grealish, who contributed three assists in a brilliant display.
Grealish added another as Villa had unending joy in springing the offside trap against Liverpool's high line, with the Reds conceding seven for the first time since a 7-2 loss to Tottenham in April 1963.
Adrian's hopes of keeping a clean sheet were dashed within four minutes when his wayward pass to Joe Gomez was seized upon by Grealish, who squared for Watkins to slot home.
Liverpool did not get a penalty for McGinn's contentious challenge on Salah, while Emiliano Martinez saw a similar error to Adrian's go unpunished before Watkins latched onto another Grealish pass and fired into the top-right corner.
Salah halved the deficit, yet Villa's two-goal cushion was restored two minutes later when McGinn's wickedly deflected volley found the bottom-left corner.
Watkins completed his treble before the first half was out by turning home Trezeguet's cross and former Everton midfielder Barkley extended their lead 10 minutes after the restart, aided by a significant touch off Trent Alexander-Arnold.
Salah swept in a cool finish in the 60th minute but any hopes of a late charge were quickly extinguished by a Grealish strike that hit Fabinho to wrongfoot Adrian.
Adrian managed to stop Watkins netting a fourth before Grealish made the most of a baffling decision to try to catch him offside on the halfway line, scoring his second.
Watkins rattled the crossbar in the 85th minute but Liverpool were already set to suffer one of the most remarkable defeats in Premier League history.
What does it mean? A first for Klopp
Villa were in searing form and became the first team to put at least four goals past Liverpool in the opening half of a Premier League game since Klopp took charge in October 2015.
In fact, the only time the Reds have conceded four in the opening period of a game in any competition during the German's tenure came on the same ground, when they went down 5-0 to Villa in the EFL Cup quarter-finals.
However, on that occasion it was a second-string line-up and Klopp was not even in the dugout, as the first-team squad were away at the Club World Cup.
Watkins may have become the first player to score a Premier League hat-trick against Liverpool since Dimitar Berbatov in 2010, but he could not have done it without Grealish. The midfielder had multiple assists in the same top-flight game for the first time and created a total of five chances for his team-mates.
With Alisson to be assessed "week by week", Klopp will be desperate to have him back as soon as possible. In his 21 appearances in all competitions for Liverpool, Adrian has now committed five errors leading directly to goals. Alisson has the same amount in 92 such games.
Liverpool will hope to get back on track after the international break with a Merseyside derby against Everton, while Villa face Leicester City next.