A 2-0 defeat to Red Star Belgrade leaves Jurgen Klopp’s side needing a victory against either Paris Saint-Germain in the French capital in three weeks or Napoli at home in their final group game.
At the moment they stay top of the table on six points courtesy of goal difference and there still remain a number of permutations which will see them qualify.
However, it would be preferable to avoid a nail-biting Anfield finale which would require them to beat the Serie A side by two goals to overturn their head-to-head record against Carlo Ancelotti’s team.
Lallana, still edging his way back to full match sharpness after a period out with injury, accepts it is time for the players to step up.
“As players we’ve got to take full responsibility and make sure it doesn’t happen again,” he told LFCTV.
“It’s still in our hands: if we win our next two games we go through, but that was a great opportunity missed for us.
“[It’s going to be] very tough. That’s the Champions League—there are no teams that enter this competition that give you wins.
“It wasn’t like us and we need to move on and improve if we’re going to go through to the knockouts.
“Of course there’ll be a reaction. It’s not the first time we’ve lost games, it’s about how you react and bounce back, but we’re thoroughly disappointed to come away with nothing.”
Klopp spoke of his side losing their mojo against Red Star but stressed he did not view it as a long-term issue.
However, his side have won just three of their last nine matches—against Red Star, Cardiff and Huddersfield—and it has been generally acknowledged they have failed to hit the heights of last season.
They conceded a goal from a corner and another from a loss of possession and quick counter-attack against Red Star, both uncharacteristic for the way the team have been performing.
“It was a slow start all round really and we gave them far too many opportunities, especially from set-pieces,” added Lallana.
“We had chances but we weren’t ruthless enough, weren’t patient enough. It’s not like us.
“It’s on us to take responsibility and we need to bounce back in the next two games.”