I saw a few games like this already and it is really hard to find your mojo.
"It was a slow start all round really and we gave them far too many opportunities, especially from set-pieces", Lallana said.
"I think it made sense to make a few changes, a few we had to make and a few we wanted to", said Klopp.
To add insult to injury, liverpool found themselves 2-0 down within half an hour when Crvena Zvezda striker Milan Pavkov scored a quick brace, netting the opener after 22 minutes and again seven minutes later to give his side the lead at half time.
Liverpool tried to mount a comeback after the break but struggled to carve out clear-cut chances, condemning them to one of the worst defeats of Klopp's three-year tenure.
Klopp says the aggression and passion which characterised the Red Star display was to be expected, but felt his team failed to rise to the challenge.
They conceded a goal from a corner and another from a loss of possession and quick counter-attack against Red Star.
"The season so far, point-wise, is really successful but it doesn't feel like that for two reasons".
Red Star Belgrade manager Vladan Milojevic spoke about how important this game was for his side before kick-off and hoped home advantage would play a big role.
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Social media was full of love for Aguero and what he has meant to the Premier League since his arrival in Manchester. 'The most important thing is we need to be prepared so that what happened to Liverpool doesn't happen to us'.
Jokanovic will be well aware that Liverpool's players will be fired up to make amends.
The hosts seemed fired up by it - winger Marko Marin was shown a yellow card for protesting in the fifth minute. So we have to admit, congratulations Red Star, well deserved.
Klopp needs to find a way to utilise his new resources and rediscover Liverpool's mojo quickly to avoid an embarrassing early European exit.
The Reds will be keen to bounce back from an incredibly disappointing 2-0 defeat to Red Star in the Champions League on Tuesday, which left Liverpool needing positive results against both Paris Saint-Germain and Napoli in order to ensure qualification to the knockout stages.
"In Liverpool we controlled the game and tonight we didn't".
However, the Liverpool fan account @TheAnfieldWrap have now come back with the ideal response.
"That's a really tough job, but we have no problem with that, we go for everything". "We all have to deal with it now".
Klopp declared the result was a one off and insisted his team had nothing to worry about, despite Liverpool losing three straight Champions League away games for the first time in the club's history.