"We had the first big chance - Daniel with a very big one".
"All over the field, we didn't win the ball back well enough and the passing wasn't good enough", Milner, who captained the Reds at the Stadion Rajko Mitić, added. A win at Paris Saint-Germain this month combined with a positive result for Napoli at home to Red Star would secure a place in the knockout phase for last season's beaten finalists.
Liverpool FC have taken six points from their opening three Champions League fixtures and they will be hoping to claim the win on Tuesday night in Serbia to take a step towards reaching the first knockout round of Europe's elite club competition.
Liverpool ideally need to get a result with a tricky tie away in the French capital to come next before a potential qualification decider at home against Napoli at the end of the group.
Their 2-0 loss at Red Star on Tuesday was a major blow given they had already lost to Napoli earlier in the campaign. Four points from their last two games would be enough to guarantee the Reds' progress to the last 16.
James Milner, meanwhile, said in his post-match interview that things went wrong "from the first whistle".
And Red Star doubled their lead just seven minutes later when Pavkov bagged his second with a superb strike from 25 yards out which Alisson may feel he could have done better with.
"It was a slow start all round really and we gave them far too many opportunities, especially from set-pieces", Lallana said.
Klopp regularly conducts analysis with his players the day after a game, having reviewed the match himself at least twice but Wednesday's debrief assumed a more critical air given the nature of defeat and the precariousness of Liverpool's position in the group.
"The atmosphere, noise-wise, was not a problem for us, but after the second goal they could smell it".
"We have to make sure you can not ask that question again".
Almost three decades on, Red Star don't have a household name in their squad and needed to qualify for the group stage through the playoffs.