Barcelona's loss to Osasuna on Saturday has made the importance of the Champions League much greater.
While Barca are favourites to win the Copa del Rey, winning in Europe may be the only consolation for a disappointing league season that promised so much more last August.
A good Barca performance was required against Bayer Leverkusen today, and Pep Guardiola's men have given themselves the best chance of progressing to the next round with a 1-3 win at the Bay Arena.
This slideshow will assess the performances of the 11 starters for Barcelona.
Victor Valdes had nothing to do in this match until the 51st minute, when he picked the ball out of the net following Leverkusen's equaliser.
The Spaniard was certainly not at fault for the goal and had to stay alert a few minutes later to keep out Andre Schurrle with a good low save.
Valdes is often unfairly viewed as being the weak link in the Barca setup, but when called upon, he rarely makes the mistakes of years gone by.
He had little to do in this match, but was solid when called upon.
The Brazilian was wasteful in his free kicks, but elsewhere, he was solid and his contribution to Barca's third goal was brilliant.
His unselfish decision to pass to Messi when many others would have chosen to shoot illustrates his crossing vision and shows how important he is to his team.
Carles Puyol had to deal with very little attacking threat in the first 45 minutes and was often seen pushing forward into the attacking midfield positions as he searched to provide for his attacking teammates.
It is hard to judge his performance when he was barely tested, but similar to Valdes, he looked solid and was a rock in the heart of the Barelona defence.
The Argentine was similar to his central defensive partner as he looked to push forward as often as possible.
If I was looking to be picky, I would criticise him for a few misplaced passes in the attacking third that on another day may have been exploited with a counter-attack.
Consistency may be hard for Mascherano, as he is often in and out of the team and his performance here was in no way poor.
Eric Abidal was particularly effective in the opening 45 minutes.
One particular moment of brilliance came after covering the defensive area, holding the ball away from the Leverkusen forwards before turning and passing almost blindly to Lionel Messi.
Abidal made this skill look effortless, and at 32, still has plenty to offer arguably the best team in the world.
Cesc Fabregas is a brilliant passer, and his through ball to Alexis Sanchez for the second goal of the game illustrated this.
The midfielder has wonderful vision, and while perhaps not his greatest performance in a Barcelona shirt, when he was given the space and time, he exploited the Leverkusen defence to devastating effect.
Sergio Busquets was a surprise inclusion in the starting lineup for Barca, having missed a couple of games with a knee injury.
His early passes were effective, often picking out Fabregas well, but as the first half progressed, he began to make some tired passes that he is not known for.
I expected him to be replaced at halftime, but his inconsistency should be viewed as a minor blip.
It is fair to say that Andres Iniesta did not have one of his most memorable games for the Catalan giants.
There is nothing to suggest that he had a bad game, but when a player of his quality is substituted with 30 minutes left, it is clear he is not at his best.
It is testament to the midfielder's skill that when he produces an average performance, the level of surprise among fans is high.
Alexis Sanchez enjoyed a night he will never forget. His goals were his first in Europe, and the match was his first start in the Champions League.
He was denied a hat-trick via a super save from Leverkusen keeper Bernd Leno late on.
The Chilean would have been man of the match if not for Lionel Messi, and his goals have surely sent his team through to the quarterfinals.
Adriano covered both the left and right attacking areas well and found his teammates consistently.
While he always had an eye for goal, his main effort was high and wid.
Despite this, the Brazilian is improving with every game he plays and provides good cover for Messi when playing alongside the Argentine.
It is hard to put into words just how good Lionel Messi is.
He was Barca's main man in this match, was central to all the attacks, almost scored the goal of the tournament after wriggling through the defense and chipping onto the post and then scored from a Dani Alves cross.
Man of the match without question.