In biting temperatures of -6C at the Fortuna Arena, Tomas Chory almost warmed the home crowd when he fizzed a shot just over after Gerard Martín’s early mistake.
Fermín Lopez then did likewise at the opposite end, but in the 10th minute, a Slavia corner caused confusion, and after a deft flick on by Tomas Holes, the ball was bundled in untidily at the far post by Vasil Kušej for Slavia’s first UCL goal in five games.
The hosts’ exceptional work-rate initially kept Barça at bay, but the Spanish champions inevitably grew into proceedings, and an incisive move down the middle on 34’ – with Frenkie de Jong feeding Fermin for a precise shot inside the right post – saw them draw level.
Four UCL goals for the winger then became five just eight minutes later, when he let fly from outside the box past a helpless Jindrich Stanek.
However, Joan García was equally nonplussed on 44’, when the hosts unexpectedly grabbed an equaliser, with Robert Lewandowski heading into his own net from a Slavia corner. That set the tone for a potentially frantic second half where one goal could clinch victory.
Pedri almost gave Barca the lead in the opening minute of the second half, and Frenkie de Jong had a goal ruled out for offside shortly after, before Raphinha skied a presentable chance as the visitors pushed hard for a third.
What looked like a hamstring injury to the Blaugranes No.8 saw Dani Olmo replace him on the hour. Shortly after, Staněk had to go full length to keep out Lewandowski before Olmo arrowed a right-foot shot into the top corner just three minutes after coming on.
And in his eagerness to atone for scoring at the wrong end, the Polish international secured all three points for Barca with 20 minutes to play, after he got on the end of a drilled Marcus Rashford cross.
The result means Barcelona have now won eight of their nine UCL games against Czech sides (D1), and gives them an outside chance of automatic qualification with one game remaining – a home clash against Copenhagen, for which they will be overwhelming favourites – in the league phase.
As for Slavia, they’ll be playing for mere pride in Cyprus against Pafos.
Flashscore Man of the Match: Fermin Lopez (Barcelona)