Paris St-Germain 2-1 Liverpool: Reds need to improve attack to make Champions League progress - Stephen Warnock
It is not a problem Liverpool have faced very often under Jurgen Klopp but, if they are going to beat Napoli next month and reach the Champions League last 16, they will have to improve in attack.
The Reds often blew teams away last season on their way to the final, but it is a different story at the moment - as we saw in Wednesday's 2-1 defeat at Paris St-Germain that has left their progress in the balance.
From 2-0 down, Liverpool got back in the game through James Milner's penalty just before half-time, but they did not cause PSG anywhere near enough problems as they searched for an equaliser after the break.
That was partly down to how well PSG defended, but it is not the first time it has happened in recent weeks - this defeat means Liverpool have lost all three of their away games in Group C, with Milner's spot-kick their only goal on the road.
Yes, they look a lot more solid at the back, but they have not been attacking with the same fluidity that we expect, or creating the same number of chances.
Every time I watched Liverpool last season, they always looked dangerous, and I always thought they were capable of doing something to change the game at any moment - but that is not the case right now.
Front three are not firing at the moment
I just don't feel that Liverpool's front three are clicking in the same way they have done in the past.
Sadio Mane was outstanding against PSG, and was the one Liverpool forward who looked up for the fight. He got into some good areas, ran at his full-back whenever he could and tried to make things happen.
But Roberto Firmino was very poor. He did not hold the ball up, or do his usual job of bringing other people into play. Too many passes were misplaced, and his touch was not great.
And I know everyone is talking about Mohamed Salah being back in form, but I don't see it myself.
I still think he is out of sorts - he is trying to play as an individual and is not enough of a team player - and that was the case on Wednesday too.
What have Liverpool lost from their attack?
It is not just down to the forwards, though. As former Liverpool defender Mark Lawrenson said on the Football Daily podcast that we did together after the PSG game, they are not getting the same supply they did last year.
As good as Liverpool's midfield three are at protecting their back four and making it difficult for the opposition, they do not get forward much.
That is the biggest difference between this season and last, and is part of the reason why their defensive record is so good.
Every time Liverpool go forward now, Milner and Georginio Wijnaldum hold back when, previously, the team would have midfield runners going beyond their front three.
That occupied opposition defenders and freed up space for Mane, Firmino and Salah - but it does not happen as often any more, and it is an element they have lost from their attack.
Long-ball Liverpool playing fewer intricate passes
The worrying thing I saw against PSG was how many long balls Liverpool played forward. Again, that happened because their midfield was sitting so deep.
Instead of the dynamic and intricate inter-play we saw from them last season, when they were trying to find the front three with 10 or 15-yard passes, they are playing balls up to them from 30 or 35 yards instead.
That is not the kind of play you would associate with Liverpool but it is a change Klopp made in pre-season and he has carried it through the start of this campaign.
It has been effective in the Premier League - Liverpool are second, still unbeaten and have only conceded five goals in their first 13 games - but it has not worked for them away from home in Europe.
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Less pressing is part of the problem too
How could Liverpool find a better balance between defence and attack? Well, we spoke on air about how they could switch to having two sitters in midfield and pushing Xherdan Shaqiri ahead of them, behind the front three.
That would bring a different dynamic but, again, I don't think it just comes down to tweaking one part of the team, because so much is different to last year.
The way the front three presses the opposition has also changed, which again is something that will have come from Klopp.
He could be thinking that if he wants to save their legs for when they attack, then he doesn't want them closing defenders down as much.
But, when they were doing that, the Liverpool midfield could get close up to them, and the defence could push high up the pitch too.
So much of the way they hurt teams stemmed from them winning the ball back in those areas, and this season it does not seem like they have got that same edge in the final third that they got from playing their pressing game.
Now is the time to find out how good Liverpool really are
For some fans, everything that Klopp's side did last season - with the success they had in getting to the Champions League final - came from them playing a certain way.
The Liverpool of last year went after teams, and took the game to them by going on the attack. They were great to watch.
When the Reds swept West Ham away on the opening weekend of this season, I walked away thinking 'what a performance', and that they are the same team they were last year - but we have not really seen them do anything similar since.
The change in style has not impressed some supporters but you only have to look at the Premier League table to see there is lots to be positive about, despite this lack of fluidity that I have been talking about.
After 13 league games last season, Liverpool were sixth in the Premier League, 14 points behind leaders Manchester City - it is Klopp's changes that have closed that gap.
They still have a chance of progressing in the Champions League too, although it will take a big performance to get the result they need against Napoli.
This is the time we are going to see how good they really are - how strong their squad is, and how they can adapt to the different questions being asked of them in the Premier League and in Europe.
They have not been playing particularly well up until now, but it would not surprise me if they clicked into gear in the next few weeks.
The international breaks during the first few months of the season can be very frustrating when you are working on things as a team, because all your players keep disappearing and it is easy to lose your momentum.
But Klopp knows now he has got his players together until March, so he can work on things week in, week out - and try to bring back some rhythm to their attacking play.
Stephen Warnock was speaking to BBC Sport's Chris Bevan.