Liverpool v Barcelona: Champions League comeback would be greatest in their history

If Liverpool come out of Tuesday's second leg against Barcelona and they are in the Champions League final, it would be the Reds' greatest result ever.

They have obviously had some big ones before and I have been there to play in or watch most of them, but because of the way Barcelona are, and particularly because of the genius of Lionel Messi, if Jurgen Klopp's side get through this tie then this would be a recovery like nothing else I have seen before.

Of course people will read that and ask "what about Istanbul?" - when Liverpool famously fought back from being 3-0 down at half-time against AC Milan to win the 2005 Champions League final, but that was slightly different.

That performance was absolutely brilliant, but it basically was just down to them gambling everything to get back in the game and throwing everyone forward.

Do that again this time, and the tie will probably be over within a matter of minutes.

After their 3-0 defeat at the Nou Camp, Liverpool's situation is already difficult enough, but another Barcelona goal would leave them needing five goals to go through, and that is just not going to happen.

So, Liverpool will have to be very, very sensible in how they go about things, and play with the handbrake on.

As hard as is it going to be for them, at least they have shown they can win that way before.

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Reds need control, not a rollercoaster ride

On the face of it, what Liverpool need to get back into the tie on Tuesday is the kind of attacking play they produced on their way to last year's final, when they tore into teams like a swarm of bees.

When they ripped Manchester City and Roma apart by scoring bursts of goals at Anfield, they had spells where they put the opposition under such immense pressure that they made even outstanding players look ordinary, then held on to see out the game.

They have not played like that for a while, though, and if they are going to find a way out of their predicament, it is likely they are going to have to do things differently.

What I think Liverpool will look for this time is a performance like their one in the last 16, when they beat Bayern in Munich by controlling the game, not turning it into a rollercoaster ride.

They are certainly capable of it because that is the way this team has evolved - they don't have to play at 100mph to win anymore.

Liverpool have already showed that side of their game with some of their play in the Nou Camp in the first leg, only this time they will obviously have to take their chances.

On that note, it is a huge blow that Mohamed Salah is out after his head injury against Newcastle on Saturday.

Without him and Roberto Firmino, who is also injured, it is going to be a lot harder for Liverpool to hurt Barca whatever their approach.

Reds' mentality is not in doubt

One thing I am not worried about here is Liverpool's mentality.

They will believe in themselves at the start of the game and, if things are at all close, at the end too.

I was not surprised to see that Liverpool's substitutes have scored more goals - 12 - than any other team's in the Premier League this season, and there have obviously been some very important ones in there too.

Klopp has built a team that is relentless, and they have shown all season in their pursuit of the Premier League title that they are capable of digging themselves out of a hole when the pressure is on.

The kind of resilience they showed again at the weekend when they won at St James' Park will be needed by the bucketload here - but on its own that will not be enough.

Of course, the crowd will play their part too.

As daft as it might sound, I'm hoping the weather is cold, cloudy and rainy on Tuesday night. That way it will go dark earlier, which I always think helps.

I played at Anfield hundreds of times, and the atmosphere was always better on a murky and mucky night under the lights than a beautiful spring or summer evening with the sun shining.

How do you stop the 'Little Genius'?

The problem in talking about why Liverpool have still got a chance is that also you have to remember why they are in this position in the first place - Lionel Messi.

Clearly Liverpool need to score some goals, but they also need to stop him, somehow.

To do that, they will need to play in Barcelona's half as much as possible because, as brilliant as Messi is, I haven't seen him score from his own half yet.

Messi has scored 14 more Champions League goals against English clubs than any other player

If Liverpool do manage to get some control of the game, and see lots of the ball in Barca's territory, then it is possible that they can negate Messi a bit.

But, even if that works, you just know there will be a spell in the game where he will come alive and then it will be a case of "hang on to your hats".

Mark Lawrenson was speaking to BBC Sport's Chris Bevan.