"The start was intense, that was clear", Klopp said.
Liverpool have won just three of their last nine matches, against Red Star, Cardiff and Huddersfield. The result puts them behind the eight ball with games to come against Paris Saint-Germain and Napoli.
As it happens, Liverpool can afford to draw in Paris and still qualify from the group and you could see them beating many of Europe's top sides over two legs, as they showed previous year.
A loss to French champions PSG would leave them facing a nail-biting shoot-out with Napoli and Liverpool midfielder Lallana knows his team have no excuses for their predicament.
Liverpool have three victories in their last nine matches in all competitions - Red Star and Cardiff at home and Huddersfield away - and while not playing well was acceptable when they were winning, it takes on a different complexion after results like that in Belgrade. Four points from their last two games would be enough to guarantee the Reds' progress to the last 16. Spurs face an uphill task after taking just four points from their opening four games, while Liverpool's slip-up in Belgrade has left them with plenty of work to do to qualify for the knockout stages.More news: Cameroon parents anxious over lack of info on abducted children
With the confidence flowing, Pavkov then doubled Red Star's advantage six minutes later, holding off the challenge of Georginio Wijnaldum before steadying himself and firing home from 25-yards out. They have the three points, we have nothing.
"It's hypothetical, but if we score with one of them then the game can change".
But Liverpool should have been in front in the 17th minute when the ball ran kindly for Daniel Sturridge inside the six-yard box, but the England global somehow managed to blaze over the bar when completely unmarked.
"The atmosphere noise wise was not a problem for us".
But It was Red Star marksmen Pavkov who would catch the eye in the Rajko Mitic Stadium.
'We need to win our games, it's on our shoulders, we have some good sides to play and it's in our hands but we will have to play better than we did tonight.