Man Utd 0-1 Barcelona: United have the tools to turn tie around - Dion Dublin analysis
The biggest positive that Manchester United can take out of Wednesday's defeat by Barcelona is that they only lost by one goal.
United did not do enough at Old Trafford to deserve anything from the first leg of their quarter-final, but the scoreline means they still have a chance in this tie.
Of course, beating Barca in their own back yard is going to be extremely difficult but I believe United boss Ole Gunnar Solskjaer has got the tools to do it.
If they have a positive attitude, then they can put Barcelona under pressure - we saw that for spells of this first leg.
United only need one goal to level things up and I don't even think they need to score it early on.
For as long as the score stays at 1-0 on aggregate, United will be in the tie and they will retain a glimmer of hope - just as they did late in the game in the last round against Paris St-Germain, and we know what happened there.
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'A passive start, but United improved'
United were far too passive in the early stages against Barca. Their approach seemed to be to let them have the ball, and then try to hit them on the break.
I don't expect that when I come to Old Trafford. I want to see United set up as if to say, "this is our home, and we are not going to allow you to come and dominate us".
It was only in the second half that Solskjaer's side really took the game to their opponents. They looked sharp, and the tempo was good.
By playing quicker passes they were not allowing Barca to settle, which is exactly what Barca were doing to them for the entire first half.
In total, United's good spells probably only lasted 20 to 25 minutes out of the 90, but those were the times when they were pressing high, and getting players into the Barcelona box.
'Squeeze Barca and get men forward'
There was a moment early in the second half from a Barcelona goal-kick that really stood out for me as a sign of United's intentions that the game would now be played on their own terms.
They squeezed Barcelona high with Romelu Lukaku down the left, Paul Pogba down the middle and Marcus Rashford on the right, and it left Barca goalkeeper Marc-Andre ter Stegen no option but to go long.
When his clearance came, Chris Smalling won the header near the halfway line, and United were back on the ball and playing in the Barcelona half.
On another occasion after the break, Pogba was on the ball and played a pass out to Ashley Young on the right, then darted into the box.
Scott McTominay followed him, Diogo Dalot had attacked the far post and Rashford and Lukaku were in there too.
Those kind of things are what I want to see United doing more of in the second leg.
They are going to have to choose their moments for their players to get forward, but unless they do, they are never going to hurt Barca.
'Pogba needs people to make runs for him'
United did not manage a shot on target on Wednesday, and they did not really use the ball well enough when they got possession.
Pogba was the player expected to play the biggest part in unlocking the Barcelona defence, but we did not see enough of the creative side of his game.
He will have to do much better next week, but he can only do that if his team-mates are making the forward runs that allow him to play those sort of passes.
Lukaku should be doing exactly that. He did not manage a single shot in the first leg but I actually thought he played well.
He held the ball up and was very reliable in possession, but all of his work was a long, long way from goal.
If United are to have any joy at the Nou Camp, they need to get him in the box and give their wide players more to aim at, because firing the ball into the Barcelona area was clearly part of Solskjaer's plan.
Young was trying to get the ball in there as much as possible but Barcelona's defenders made that really difficult for him, and a lot of his crosses were blocked.
United's best chance did come from Young's right flank, though - a Rashford cross that Dalot headed wide.
'Liverpool licking their lips, whoever goes through'
United were not at their best in the first leg, but I don't think Barcelona played particularly well either.
They dominated the game for long spells, but their front three of Lionel Messi, Luis Suarez and Philippe Coutinho were not really firing.
Even so, when Barca had possession, whoever was on the ball seemed to have a lot of options.
They did the simple things very well and created more chances. Ernesto Valverde's side deserved their win and they have to be favourites to go through.
Barca are not the force they were, though, and if Liverpool finish the job against Porto then they will be licking their lips whoever they end up playing in their semi-final.
Liverpool obviously have to make sure of their own progress first but I don't think they will care who they face next.
With their pace and inventive attacking play, they will probably feel they can catch out either of these defences quite easily, and they will fancy their chances of making the final for a second successive season.
Dion Dublin was speaking to BBC Sport's Chris Bevan.