The 24-year-old forward was thrilled with the success, which has suddenly boosted Red Star's chances in Group C, and said it would be tough to put behind him quickly.
Robertson accepts they have not been at their best over the last three months and that the high standard they set in the previous campaign is now what they will be judged on.
"I do not say it is serious we lost two times, but of course we have to make sure that it will not happen again, otherwise it will be hard, because the next game is already an away game again, and then a tough home game".
Liverpool had a lucky escape at the start of the second period - the referee failing to award Red Star a penalty when a shot struck the arm of James Milner. But, similar to the first half, in different situations we had the ball in the box and we could not really finish or they got a leg in between. He knows you can't win on hugs alone, and will be doing everything possible to try to lift this Liverpool side back up to the levels we all know they can play at.
"All over the field, we didn't win the ball back well enough and the passing wasn't good enough".
But the introduction of Roberto Firmino and Joe Gomez did little to galvanise the Reds and Red Star held on to claim a famous victory.
"I think that message by not picking your strongest team to start with would have an effect with some of the players who did start".
"At half-time, we tried to change a few things and did that".
The first real scare for Napoli came on 23 minutes. "The gaffer, win or lose, always speaks more the day after because that's when he can clear his head and that's where he gets the best out of us". However one stat from last night's game is causing rage in a big section of the fanbase. The Reds have to play PSG and Napoli in their final two games, and they'll likely need at least four points to feel good about their chances.
"I think the message it sends to the rest of the players was, 'You won 4-0 last time we'll be fine again tonight'". We have to do better, we have to do better. They deserved it in the end with the passion they showed. There were a lot of moments when we could get in control of the game and we didn't do it, we made the wrong decisions.