The return leg is set for 15 April at Dortmund's Signal Iduna Park, and the stakes couldn't be higher for the Catalan giants.
This midweek clash against Dortmund is a make-or-break moment for Barcelona. Not only are they fighting for a spot in the semi-finals of Europe's elite competition, but they're also desperate to lift spirits after a frustrating draw against Real Betis last weekend.
The Blaugrana have no choice but to dust themselves off and secure a victory that gives them a fighting chance heading into the second leg in Germany.
Head coach Hansi Flick has made it clear he'll field his strongest available line-up, despite injury setbacks ruling out Dani Olmo and Marc-Andre ter Stegen. Assuming Inigo Martinez recovers in time to start, Barcelona's XI is all but settled - bar one key position.
Wojciech Szczesny is expected in goal, with Jules Kounde, Pau Cubarsi, Inigo Martinez, and Alejandro Balde forming the backline.
In midfield, Pedri and Frenkie de Jong are nailed on, while Lamine Yamal, Robert Lewandowski, and Raphinha lead the attack. The only question mark hangs over the attacking midfield role, where three players are in contention.
Ferran Torres has staked a strong claim with his recent form. While he didn't find the net against Betis, he set up Gavi's goal with a pinpoint assist.
The Valencia-born forward has been a standout this season, and fans won't forget his brace in Barcelona's 3-2 group-stage win over Dortmund earlier in the campaign.
Flick has praised Torres' impact, saying after that match, "Ferran showed his quality and fight, he's vital for us." His inclusion would signal an all-out attacking approach.
Gavi, meanwhile, has boosted his chances after a match-winning display against Betis. The young midfielder scored early and ran the show, earning plaudits from Flick, who said post-match, "Gavi's energy and heart are what we need." After a tough season plagued by inconsistency, a start here could be the confidence boost the 20-year-old craves.
Then there's Fermin Lopez, the wildcard option. Flick considered him for the Betis game but opted for Gavi instead. If Torres offers firepower and Gavi brings grit, Fermin strikes a balance between the two, blending attacking flair with defensive nous.
With two training sessions left before kick-off, Flick has a big call to make.
The debate's heating up, but one thing's certain: Wednesday's result could define Barcelona's season. A win would set them up nicely for the trip to Dortmund, anything less, and the pressure will be on.