It's the great unspoken fear loitering in the back of the minds of Liverpool supporters and, most probably, the squad too. And it's ensuring the Reds are doing everything to avoid the momentum of such an encouraging season being checked.

While the remarkable debut campaign in the Anfield hotseat for Arne Slot continued with a 2-1 home win over Lille on Tuesday that secured qualification to the Champions League knockout stages, almost all of the players the Reds boss inherited have been here before. Twelve months ago, in fact, when, as with this season, Liverpool began the New Year with very real sights on an unprecedented trophy quadruple.

That it didn't happen was no surprise given no team in history has ever managed such a feat. But the manner in which the Reds disappointingly tumbled out of Europe and the FA Cup before, most painfully, falling away in the Premier League title race during the closing months hasn't been forgotten.

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And Liverpool skipper Virgil van Dijk - who has now equalled Phil Neal's record for most victories by a Reds player in their first 50 European Cup appearances - believes the experience and lessons of those chastening weeks cannot be ignored.

“I think you have to learn from difficult moments and moments that don't go your way," he says. "Most of the guys in the dressing room now have experienced last year and that should make you better, make you aware of how to deal with certain situations and circumstances, and you should be better equipped. Let's see.

"At the moment I am looking at our team and we are very calm, we are working our socks off each and every day, each and every game, and we need everyone fit, healthy and in form and that's the aim. Going into every game with the mentality it is game by game. That's how it's always been the case. It's a nice ride, I think you should enjoy it as well and I will definitely do it."

The win over Lille - which was more comfortable than the scoreline suggests - means Liverpool were the first team in the new-look Champions League opening stage to progress direct to the last 16 after seven wins out of seven, with a point at PSV Eindhoven next week securing top spot above Barcelona, who have also qualified.

And of avoiding the need for a two-legged play-off in February, Van Dijk adds: "That is why we worked so hard to make sure we are as soon as possible qualified and doing it in the right way. Obviously seven wins out of seven is a very good start.

“I've heard if you are one or two you don't play (each other) until the final. Every game we try to win and that will definitely be the case when we go to Holland for our last game.

"(Against Lille) it was always going to be tough as they were unbeaten for 21 games. But there is no point in thinking about the knockout stage where we are now. We won't. Now it is time to recover as quickly as possible and be ready for the weekend."

With Liverpool boasting a perfect record in the Champions League and six points clear at the Premier League summit with a game in hand, opponents have been lining up to declare Slot's team the best in Europe at present. Van Dijk, though, is refusing to become carried away with such high praise.

“I think it sort of gives confirmation we are on the right track," he says. "We work in every game so hard to be a very difficult team to beat. When other managers are giving you praise for not only the way you attack but defend as well as a group and the bodies you get back behind the ball, that is only a good sign and credit to all the hard work each and everyone has been putting in. That's the only thing we should take from it and other than that it is just focusing on doing it and staying consistent.

“At this point we haven't achieved anything but we are in a very good place and a place that other teams playing in both competitions wants to be in and are fighting for. But we have to stay calm and we will.

"If we have surprised ourselves, I don't know. I know this squad already for a couple of years so there are not many changes; obviously the biggest change is the manager and the staff and how he wants us to play and I think we adapted to that pretty quickly, I don't think there are major tweaks but what has been changed I think the boys have been doing brilliantly and that has been shown and we have to keep that going until the end of the season and hopefully we can get the reward for that."

Van Dijk will be expected to retain his place for Saturday's Premier League visit of Ipswich Town, which will mark his 300th appearance for Liverpool.

And of reaching the milestone, he says: "Proud is the first word which comes into my mind. Longevity is always an important thing and I am very proud on Saturday I could play my 300th game for the club. It will be a very proud day and I'll be a very proud man. Let's keep going."