From Gtech Community Stadium - Brentford maintained their impressive big game record this season with a 3-1 win at home to Liverpool.
The hosts were missing Ivan Toney due to a leg injury, but still made life difficult for the Reds and were deserved victors on Monday evening.
After Brentford failed to clear an early corner, Harvey Elliott's deep cross was helped on by Virgil van Dijk, and though it was impressively tipped over by David Raya, the offside flag was later raised.
Liverpool continued to threaten early doors as Mohamed Salah swivelled past Zanka and set through Darwin Nunez, who rounded Raya but saw his effort cleared off the line by Ben Mee.
At the other end, a cross from Rico Henry was met by the head of Bryan Mbeumo, but he couldn't keep his effort on target.
The Cameroon international squandered a great chance to give Brentford the lead shortly afterwards. Christian Norgaard robbed Nunez of possession on the edge of the Bees box and quickly found Yoane Wissa, who in turn sent Mbeumo racing away, only for Alisson to deny him at close range.
From the resulting corner, Brentford did take the lead when Mbeumo's cross was diverted into the Liverpool net by Ibrahima Konate's knee. The goal stood after a lengthy VAR checked cleared Mee of handling the ball before it struck the Frenchman.
The Reds nearly levelled when Alex Oxlade-Chamberlain cleverly found an open Kostas Tsimikas when surrounded by four defenders, but Raya saved his near-post attempt.
Thiago nearly gifted Brentford a second following a mix-up with Van Dijk, allowing Mathias Jensen to run through on goal, but his half-volley was deflected over by the retreating Liverpool backline.
And from that corner, the hosts had the ball in the net again. Norgaard's flick-on was well saved by Alisson, who then denied two rebounds from Ethan Pinnock, only for Wissa to tap in from a yard out. However, the offside flag was correctly raised against the forward and the goal was chalked off.
Liverpool's inability to defend Brentford corners continued as Wissa seemed to half-volley them into a two-goal lead. However, VAR ruled it out for offside against Mee, whose deflection sent the shot into the top corner.
But the Reds inexplicably gave the ball away from that free-kick and Alisson was unable to claw Wissa's header from Jensen's superb cross away in time, with Brentford now legally going 2-0 up.
Klopp made three changes at half-time in order to help stem the tide, throwing Naby Keita, Andy Robertson and Joel Matip on for Elliott, Tsimikas and Van Dijk.
Whatever the German said at half-time seemed to work as Liverpool had the ball in the net minutes after the restart. Thiago's wonderful ball over the top was met by Nunez and he dinked it over Raya, only for VAR to pull it back for a marginal offside against the Uruguayan.
But like Brentford in the first half, Liverpool responded to a tight offside call by scoring a legal goal. Trent Alexander-Arnold cut in off the right and his curling cross was nodded in by Oxlade-Chamberlain.
The ball belonged to Liverpool in the second half, but they went a long stretch without a clear sight of goal - Nunez went closest with a horrendously dragged effort from just inside the box after 70 minutes.
And Liverpool were made to pay as Mbeumo added Brentford's third in the dying embers. Keane Lewis-Potter pick-pocketed Keita in midfield, and Norgaard's crossfield ball was met by Mbeumo, who outmuscled Konate and slotted past Alisson.
Pinnock and Henry managed to scramble away Salah's effort at the last as the visitors sought to claw their way back into the contest again, but that was the best they could muster and Brentford took all three points.
Brentford player ratings (3-5-2)
GK: David Raya - 7/10 - Made a string of brilliant saves, particularly in the first half.
CB: Zanka - 7/10 - Picked up a second-minute booking for a foul on Nunez, but looked very assured from then onwards.
CB: Ethan Pinnock - 8/10 - Sliced a couple of clearances but was largely fine. Kept Nunez quiet, which is a hard ask.
CB: Ben Mee - 8/10 - Involved plenty at both ends, winning tackles and forcing goals.
RM: Mads Roerslev - 5/10 - Looked rather timid and didn't offer a lot offensively.
CM: Mathias Jensen - 8/10 - The creator of Brentford's biggest chances, earning an assist for Wissa for their second goal.
CM: Christian Norgaard - 8/10 - Swept up well and was excellent at starting counter attacks.
CM: Vitaly Janelt - 6/10 - Not his brightest day on the ball but ran hard and contributed defensively.
LM: Rico Henry - 8/10 - Dominated his flank. Even atoned his defensive errors in the same phases of play.
CF: Bryan Mbeumo - 8/10 - An excellent facilitator and his set piece delivery was spot on. Made himself the hero with the clinching goal.
CF: Yoane Wissa - 8/10 - While he lacks Toney's physicality, Wissa did a great job of making himself a nuisance, earning a place on the scoresheet.
Josh Dasilva (73' for Jensen) - 5/10
Keane Lewis-Potter (73' for Wissa) - 6/10
Saman Ghoddos (88' for Janelt) - N/A
Sergi Canos (88' for Mbeumo) - N/A
Mads Bech Sorensen (90' for Henry) - N/A
Thomas Frank - 8/10 - Another big game in which the Dane got his game plan spot on. Exposed Liverpool's weaknesses excellently.
Liverpool player ratings
GK: Alisson - 7/10 - Kept the score down with some brilliant saves. Came an inch away from replicating Gordon Bank's famous 1970 save vs Brazil.
RB: Trent Alexander-Arnold - 5/10 - Targeted defensively but was one of Liverpool's most potent creators.
CB: Ibrahima Konate - 3/10 - Caught in the chaos and changed the game with his own goal. Outmuscled by a much smaller player in Mbeumo.
CB: Virgil van Dijk - 4/10 - Defended with a bit more emphasis than usual but it wasn't enough to save him from a half-time hooking.
LB: Kostas Tsimikas - 3/10 - Constantly roasted in his 45 minutes on the pitch.
DM: Fabinho - 5/10 - After a tumultuous first half, Fabinho looked much more assured in the second and did his own job well.
CM: Harvey Elliott - 4/10 - Effective in wide areas but that was it, if you needed more proof his long-term future isn't in midfield.
CM: Thiago - 5/10 - Like Fabinho looked more like his old self after the break.
RW: Mohamed Salah - 5/10 - Showed excellent poise physically and technically, but mainly in wide areas and not in dangerous ones.
CF: Darwin Nunez - 4/10 - Looked sharp early on but found chances difficult to come by.
LW: Alex Oxlade-Chamberlain - 6/10 - Took his goal well but lacked the dynamism to lead attacks.
Andy Robertson (46' for Tsimikas) - 6/10 - Brought the energy that Liverpool lacked.
Joel Matip (46' for Van Dijk) - 6/10 - Better than Liverpool's other centre-backs but that's not saying much.
Naby Keita (46' for Elliott) - 5/10 - Didn't shy away from the ball but did give it away for the third goal.
Curtis Jones (84' for Oxlade-Chamberlain) - N/A
Jurgen Klopp - 4/10 - Liverpool defended without intensity and they were punished for it.