Liverpool's Champions League campaign rocked after shock defeat by Red Star Belgrade

Red Star Belgrade 2 Liverpool 0: For last year's runners-up, reaching this year's round of 16 is suddenly in doubt

Liverpool were left stunned by their opponents (Reuters)

Few clubs know the potential of a hostile atmosphere on a European night better than Liverpool, yet at the Rajko Mitic Stadium on Tuesday night, Red Star Belgrade gave Jurgen Klopp's side a bitter taste of their own medicine.

Finalists in May, Liverpool's hopes of qualifying for this year's knock-out stages were surprisingly dented in Serbia. Two unanswered Milan Pavkov goals in the space of seven first-half minutes gave Red Star their most famous victory in continental competition since winning the European Cup in 1991.

Klopp's players simply had no answer to a side unrecognisable from their 4-0 defeat at Anfield a fortnight ago, this time buoyed by their impassioned home support. Red Star's last defeat on this ground was over a year ago. This is a fortress and one they invariably defend.

Even so, with a trip to Paris Saint-Germain next in Group C followed by a visit from Napoli at Anfield, to take three points was deemed vital. To leave with nothing is damaging. The draw between

During the warm-ups, the Rajko Mitic greeted the Liverpool players with a bit of call and response - one end provided "Fuck you", the other "Liverpool". The crowd then chanted the same in unison as Klopp's players left the pitch, though any mounting sense of menace was spoiled by the club mix of Abba's 'Gimme, Gimme, Gimme' that followed.

Though as kick-off approached, the noise picked up again, especially as those same Liverpool players made their way back out, down this stadium's long underground tunnel with their journey displayed to the crowd via the big screen. They could be forgiven for suddenly feeling intimidated. They certainly started as if scared.

Red Star, meanwhile, fed off this fear. Right-back Filip Stojkovic was rallying the crowd as early as the third minute. He and his team-mates were assertive and assured of themselves, everything a sloppy Liverpool were not. Vujadin Savic, their captain, came closest to an opener, glancing an effort past the left-hand post on the turn.

Milan Pavkov rises highest to put Red Star ahead (REUTERS)

The night may have taken a different course had Daniel Sturridge, selected ahead of Roberto Firmino, converted an early, gilt-edged opportunity. Instead, he lifted the ball clear of the bar with Red Star's goal was gaping after Sadio Mané and Andrew Robertson's combination work down the left.

A Liverpool goal would not have truly reflected the balance of play in those opening stages however and Red Star would ultimately establish a deserved lead. When an attempt from range by El Fardou Ben Nabouhane was only parried by Alisson, a corner followed and Pavkov nodded home.

It was the sort of set-piece goal Klopp's Liverpool were once renowned for conceding, one that Virgil van Dijk's arrival had supposedly solved, but the world's most expensive defender was left beaten by Pavkov's run from deep. Adam Lallana had passed the Red Star striker on without ensuring that Van Dijk was free to receive him.

The crowd erupted in low, triumphant bellow, the crescendo they had long been building towards. A Red Star substitute joined the celebrations on the pitch, leading referee Antoino Mateu Lahoz to remind him of conduct and, presumably, that it was still just the 22nd minute.

Milan Pavkov celebrates his second for the hosts (Getty)

Pavkov, though, would inflict further damage before the half-hour mark. Milner's loss of possession in midfield was costly, allowing Marko Marin to quickly break and lay the ball to the scorer of Red Star's first. Pavkov brushed Georgino Wijnaldum away, checked his run back inside then fired at some 30 yards. Alisson, flat-footed, moved too late.

Klopp often looked incandescent on the touchline during this dismal first half and made his frustrations clear at the break, replacing Sturridge with Firmino and taking a below-par Trent Alexander-Arnold off for Joe Gomez.

Liverpool improved, if only because Red Star now sought to protect a lead rather than establish one, but their play was still devoid of its usual fluency. There was still more careless mistakes too, whether it was Mohamed Salah's woeful corners, Mané dribbling the ball out of play on the touchline or several players slipping on the surface underfoot.

Daniel Sturridge is closed down by Milos Degenek and Filip Stojkovic (Reuters) (Action images via Reuters)

Twice Liverpool hit the woodwork, with a Robertson cross dropping on top of the bar and a scuffed Salah grazing the outside of the upright. Neither, though, were particularly close to troubling goalkeeper Milan Borjan.

Salah could have capped off his muted performance with a stoppage-time goal but, when the ball broke kindly, his rushed attempt was easily held. There would not even be a consolation.

At full time, Klopp could have looked to the statistics, noted Liverpool's 23 shots to Red Star's 10, and attempted to mount a defence of the performance. Yet the great volume of attempts did not make up their lack of quality. When asked to put his finger on what went wrong, the Liverpool manager pointed out: "I've only got 10 fingers."

For last year's runners-up, reaching this year's round of 16 is suddenly in doubt.