"Can you put your finger on what went wrong?" Klopp was asked following the final whistle. "I only have 10 fingers!" came the reply. Minutes earlier, James Milner had been questioned on exactly where the problems originally orchestrated. "From the first whistle," was his riposte. Full marks for honesty, because there was nothing else to credit on the night.
Ironically it was 45 years to the day, Liverpool suffered a second consecutive 2-1 defeat to Red Star Belgrade that was later cited as a key turning point to the Reds domination across Europe during the 1970's.
Lessons learnt from Serbia that night were fundamental to the triumph the Reds later sustained three and a half years later when they lifted their first European crown.
Any damage from tonight's defeat can certainly be repaired. However, the remedy that will repair the sickness suffered in Serbia tonight will be no quick fix.
Stomachs will be further unsettled as of a result of having been previously beaten by Roma and Napoli, it means it's the first time Liverpool have lost three successive games on their travels in Europe's elite club competition since 1979.
Jürgen Klopp will hope that the embarrassment suffered tonight from the Serbian champions will be the catalyst for improvement and the beginning of delivering key results.
Milan Pavkov’s first-half brace was a testament to the desire, tenacity and spirit shown by a rejuvenated side that was humbled at Anfield only two weeks ago.
For Liverpool, it was a reminder of the verve and swagger that has faded from the side that dazzled all the way to the final last campaign.
However, the Reds humbling in Serbia on Tuesday night could prove timely considering the stakes of the away match in Paris following Liverpool's defeat.
There will be no room for error at the Parc des Princes in just over a fortnight's time with progression in the balance. Klopp's side simply can't afford any more slip-ups if they are to qualify from what is likely to be the tightest group to call in the competition this season.
Reds face the gauntlet in order to qualify
Following Tuesday nights disappointing defeat, Liverpool's final two Champions League group matches look about as far from ideal as possible.
The 1-1 draw between Napoli and PSG in Naples mean it's almost impossible to predict the outcome of Group C and one false move in either of these fixtures could see the Reds European dreams die before they even got started.
However, the Reds only have themselves to blame for a chastening defeat that destroyed their hopes of taking control of the group.
13 days have passed since Liverpool's dismantling of Belgrade 4-0 at Anfield. Incredibly Klopp's men were found wanting by the Serbian champions, who celebrated wildly after securing their first triumph in the competition since 1992.
A night where the Merseysiders failed to capitalise and seal their own destiny was further damaged by the devastating truth that Vladan Milojevic's side showed the greater heart, the greater spirit, the greater hunger.
Changes prove costly on a damaging evening
Klopp bullishly stated before the match that Red Star had the utmost respect of his players. However, judging by the performance of the team tonight - including many individuals going completely AWOL - it's fair to say the team wilted in front of their infuriated manager.
The German manager opted to ring in a number of changes from the side that drew with Arsenal at the weekend and the decision blew up in Klopp's face. Throughout the team, there was a sense of spinelessness and a complete lack of quality. Traits that have rarely been associated with the Reds recent impressive sides.
Striker Pavkov, who cost 300,000 Euros from Radnicki and was an unused sub in the reverse fixture at Anfield repaid his price tag and some as he struck twice to send the home support into delirium.
Liverpool improved in the second period but very rarely threatened. They never looked like mounting a comeback as any form of a spark was left to die with the tragic performance.
How could have Liverpool done with Xherdan Shaqiri to ignite some quality in this match who Klopp decided to leave at home.
There is no denying the match was lost in the midfield and the performance tonight only sours the absence of Alex Oxlade Chamberlain. The former Arsenal man's willingness to get on the ball, drive at opponents, take risks and play incisive vertical passes was something the Reds completely lacked at the Rajko Mitić Stadium.
The Reds boss looked to unleash the fresh legs of Daniel Sturridge, Adam Lallana, and Joel Matip - two of whom were removed folliwing failure to impact the game.
The contest's dynamic could have completely changed had the Reds shown a ruthlessness early on.
Sturridge unsurprisingly got the nod over an out-of-form Roberto Firmino and was looking to add to his record scoring in on each of his three previous European starts for the Reds dating back to 2016. However, the Englishman squandered the visitor's best opportunity when he blazed over an effort from six yards out.
Klopp learns some hard truths regarding his players
A recurring theme of Red Star cutting through the midfield trio of Milner, Wijnaldum and Lallana became an increasingly frustrating sight and their inability to silence the crowd allowed the hosts' belief to grow in numbers.
Their faith was quickly rewarded as former Chelsea winger Marko Marin swung a corner into the box and Pavkov towered over two Liverpool defenders to thunder home his header.
An eruption engulfed the whole stadium and the home side sensed their jubilation was far from over here.
Joy turned to ecstasy when Pavkov doubled proceedings. Milner squandered possession cheaply and the Serbian forward pounced, shrugging off Wijnaldum before unleashing a fierce 25-yarder into the top corner past a helpless Alisson.
The Reds enjoyed more than 80% possession in the Rajko Mitić Stadium although their dominance on the ball was let down by a lack of composure in front of goal.
Liverpool's incompetence to hit the back of the net became infuriating. Salah volleyed over, Lallana had one deflected off the line while Sturridge sliced a horror effort over to summarise a dismal first period.
Klopp was taking no prisoners as he removed Sturridge and Trent Alexander Arnold for Firmino and Joe Gomez. Divock Origi even featured for the first time since August 2017 as he replaced the ineffective Lallana.
A disappointing night met with worrying implications. Liverpool will not be able any further slip-ups if they are to qualify for the last-16 of the competition.
Klopp's men could do with the thrilling brand of attacking football the Reds played en route to Kiev last term if they are to survive in what is proving to be the competitions most unforgiving group this season.