Kuyt promised: "We will not play as badly as that again, we must improve and we will improve."
He added: "It was a bad performance. We tried to do our best and it was not good enough.
"The forwards just did not have enough of the ball, and our man of the match was Pepe Reina, that says everything about us.
"We will need a big improvement at Anfield. We know we did not play our best game against Liege, we know that as a team.
"We struggled. We could not pass the ball to our team-mates anywhere near enough.
"It was a difficult night and difficult to know what really went wrong. But the good thing was a clean sheet and that will give us the edge in a fortnight for the second leg.
"We know it was not our best game. But we want to step things up and we know there is quality in the team, we have shown that in pre-season and now we must show it in competitive matches too.
"We have some big games coming up. One of those is on Saturday at Sunderland. So we must not play like this again.
"As for the Champions League, fortunately we are still in the tie, but we definitely have to show better form than we showed in Liege. We need to score, we have to play better and we will."